KCTD7: A BTB/POZ Domain Protein Linking Protein Degradation to Neuronal Excitability and Lysosomal Function

Introduction

KCTD7 (Potassium Channel Tetramerization Domain-containing protein 7) is a human gene located on chromosome 7q11.21 that encodes a 289 amino acid cytoplasmic protein containing an N-terminal BTB/POZ (bric-à-brac, tramtrack, broad complex/poxvirus and zinc finger) domain [vanbogaert-2007-kctd7-pme-abstract]. Despite its name suggesting involvement in potassium channel tetramerization, KCTD7 does not possess transmembrane domains or function directly as an ion channel. Instead, accumulated evidence demonstrates that KCTD7 functions primarily as a substrate adapter protein for Cullin-3 (CUL3)-based E3 ubiquitin ligase complexes, thereby regulating protein degradation through the ubiquitin-proteasome system [staropoli-2012-kctd7-cln14-abstract][wang-2022-kctd7-cln5-abstract].

The protein was first linked to human disease in 2007 when Van Bogaert and colleagues identified a homozygous nonsense mutation (R99X) in KCTD7 as the cause of a severe form of progressive myoclonic epilepsy (now designated EPM3) in a consanguineous Moroccan family [vanbogaert-2007-kctd7-pme-abstract]. Subsequent research has revealed that KCTD7 mutations can also cause a form of neuronal ceroid lipofuscinosis (CLN14), highlighting its essential role in lysosomal function and autophagy [staropoli-2012-kctd7-cln14-abstract][metz-2018-kctd7-autophagy-abstract]. Current understanding positions KCTD7 at the intersection of protein homeostasis, neuronal excitability, and lysosomal enzyme trafficking, with its dysfunction leading to devastating pediatric neurodegenerative disease.

Structural Organization and Domain Architecture

KCTD7 belongs to the human KCTD (potassium channel tetramerization domain) protein family, which comprises 26 members that share sequence similarity with the cytoplasmic T1 domain of voltage-gated K+ channels [skoblov-2013-kctd-family-abstract]. Based on phylogenetic analysis of BTB domain sequences, the family is divided into seven groups, with KCTD7 classified in the C-group alongside its closest homolog KCTD14 [skoblov-2013-kctd-family-abstract]. This family arose through gene duplication from a common ancestral gene followed by divergence, leading to functional diversification across the animal kingdom. Despite the family name suggesting tetrameric assembly (as in Kv channels), crystallographic and cryo-electron microscopy studies have demonstrated that most KCTD family proteins, including KCTD7, assemble as pentamers [jiang-2023-kctd-structure-abstract].

The cryo-EM structure of mouse KCTD7 in complex with human Cullin-3 N-terminal domain (PDB: 8I79) was determined at 2.80 Šresolution and reveals a heterodecameric complex with C5 symmetry, comprising five KCTD7 subunits and five CUL3 molecules [jiang-2023-kctd-structure-abstract]. The pentameric BTB domain ring sits at the central fivefold axis, with five CUL3 molecules extending outward like arms from this core. Each CUL3 molecule contacts two adjacent BTB subunits through a primary binding interface (~732 Ų buried surface area) and a secondary binding interface (~247 Ų), creating a stable interaction network [jiang-2023-kctd-structure-abstract].

The C-terminal region of KCTD7 (residues 139-289) serves as the substrate-binding domain, responsible for recruiting specific proteins for ubiquitination. Bioinformatic analyses indicate that KCTD7 is structurally similar to KCTD5, another well-characterized family member, and both proteins form pentameric assemblies that engage substrates through their C-terminal domains while recruiting CUL3 through their BTB domains [jiang-2023-kctd-structure-abstract].

Primary Molecular Function: Substrate Adapter for CUL3 E3 Ubiquitin Ligase

The primary biochemical function of KCTD7 is to serve as a substrate adapter protein within Cullin-RING E3 ubiquitin ligase complexes (CRL3-KCTD7) [wang-2022-kctd7-cln5-abstract][staropoli-2012-kctd7-cln14-abstract]. In these complexes, CUL3 provides the central scaffold that recruits the RING domain protein Rbx1 (which in turn binds ubiquitin-conjugating E2 enzymes), while KCTD7 serves as the substrate receptor that determines which proteins are targeted for ubiquitination and subsequent proteasomal degradation.

A critical substrate of the CRL3-KCTD7 complex is CLN5, a soluble lysosomal protein whose mutations cause another form of neuronal ceroid lipofuscinosis (CLN5 disease) [wang-2022-kctd7-cln5-abstract]. Wang et al. (2022) demonstrated that KCTD7 promotes K48-linked polyubiquitination of CLN5, marking it for proteasomal degradation. Under normal conditions, this ubiquitination maintains CLN5 at appropriate steady-state levels. When KCTD7 is deficient or mutated, CLN5 escapes degradation and accumulates to pathological levels in the endoplasmic reticulum [wang-2022-kctd7-cln5-abstract].

The functional consequences of CLN5 accumulation are profound. CLN5 normally interacts with the CLN6-CLN8 complex (the "EGRESS complex"), which recruits newly synthesized lysosomal enzymes at the ER for transport to the Golgi apparatus and eventual delivery to lysosomes [wang-2022-kctd7-cln5-abstract]. When CLN5 accumulates excessively due to KCTD7 deficiency, it paradoxically disrupts this EGRESS complex-mediated enzyme trafficking, leading to impaired lysosomal enzyme delivery and lysosomal dysfunction. This mechanism elegantly explains how KCTD7 mutations can phenocopy other NCL subtypes caused by direct mutations in CLN5, CLN6, or CLN8 genes [wang-2022-kctd7-cln5-abstract].

Role in Neuronal Potassium Homeostasis and Excitability

Despite not functioning as a channel itself, KCTD7 exerts significant effects on neuronal membrane potential and excitability. Azizieh et al. (2011) demonstrated using patch-clamp electrophysiology that overexpression of KCTD7 in neurons hyperpolarizes the cell membrane and reduces neuronal excitability [azizieh-2011-kctd7-potassium-abstract]. This hyperpolarizing effect is potassium-dependent, as confirmed by studies in Xenopus oocyte expression systems [moen-2016-kctd7-glutamine-abstract].

The mechanism by which KCTD7 influences potassium conductance remains incompletely understood, but the interaction with CUL3 appears essential. One hypothesis suggests that the CRL3-KCTD7 complex may regulate the expression levels of potassium channel subunits or their regulatory proteins through ubiquitin-mediated degradation [azizieh-2011-kctd7-potassium-abstract]. By modulating the turnover of negative regulators of potassium channels, KCTD7 could indirectly enhance potassium conductance and promote membrane hyperpolarization.

Importantly, Moen et al. (2016) discovered that KCTD7 also regulates the activity of SAT2 (Slc38a2), a sodium-coupled neutral amino acid transporter that mediates glutamine uptake into neurons [moen-2016-kctd7-glutamine-abstract]. SAT2 is predominantly expressed in glutamatergic neurons, where it concentrates glutamine in dendritic compartments. This glutamine pool serves as a precursor for glutamate synthesis, the brain's primary excitatory neurotransmitter. Wild-type KCTD7 expression enhances SAT2-mediated glutamine transport, while pathogenic KCTD7 variants impair this function [moen-2016-kctd7-glutamine-abstract]. The disruption of glutamine transport may lead to inadequate glutamate synthesis in excitatory neurons, potentially contributing to the seizure phenotype through dysregulation of the glutamate-glutamine cycle.

Subcellular Localization

KCTD7 displays primarily cytoplasmic localization with additional association at the plasma membrane [azizieh-2011-kctd7-potassium-abstract]. The protein's hydropathy profile and primary sequence are consistent with a soluble, intracytoplasmic protein lacking transmembrane domains. Studies in heterologously transfected HeLa and COS-1 cells showed diffuse cytosolic localization without significant colocalization with markers for endosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, or cytoskeleton [azizieh-2011-kctd7-potassium-abstract].

In neurons, KCTD7 localization extends beyond the cell soma to include neuritic varicosities along developing neuronal extensions and neurite growth cones [azizieh-2011-kctd7-potassium-abstract]. Laser scanning microscopy has also detected KCTD7 signal at the plasma membrane, consistent with its functional effects on membrane potential. Wild-type KCTD7 shows broad cytoplasmic distribution with distinct plasma membrane signal, while certain pathogenic variants (such as R184C) display more diffuse cytoplasmic distribution with diminished membrane association and formation of cytoplasmic aggregates [staropoli-2012-kctd7-cln14-abstract].

Within the mouse brain, KCTD7 expression is widespread in neurons, including cortical neurons, pyramidal and granular cell layers of the hippocampus, and cerebellar Purkinje cells [azizieh-2011-kctd7-potassium-abstract]. Importantly, not all neurons express KCTD7, and expression is absent from astrocytes and microglial cells. The expression pattern in hippocampus and cerebellum correlates well with the clinical phenotype of KCTD7-related disease, which prominently features seizures and progressive ataxia.

Role in Autophagy and Lysosomal Function

Beyond its role in CLN5 regulation, KCTD7 has broader functions in maintaining autophagy-lysosome pathway integrity. Metz et al. (2018) conducted comprehensive studies of patient-derived fibroblasts and a yeast model (deletion of WHI2, the KCTD7 homolog) to characterize the cellular consequences of KCTD7 deficiency [metz-2018-kctd7-autophagy-abstract].

Electron microscopy of brain biopsies and cultured fibroblasts from KCTD7-deficient patients revealed characteristic ultrastructural abnormalities: abnormal phagolysosomes with accumulated lipid droplets, supernumerary lipid droplets in proximity to mitochondria, and mitochondrial cristae malformations [metz-2018-kctd7-autophagy-abstract]. Lipofuscin accumulation was observed, although it lacked the classical characteristics of neuronal ceroid lipofuscinosis storage material, suggesting a distinct pathological entity.

Functional assays demonstrated impaired autophagy flux in KCTD7-deficient cells. Patient fibroblasts showed reduced LC3-II accumulation following chloroquine treatment (which blocks autophagosome-lysosome fusion), indicating defective autophagosome formation or processing [metz-2018-kctd7-autophagy-abstract]. Immunofluorescence analysis revealed increased numbers of p62, ubiquitin, and LC3B puncta in KCTD7-deficient cells, consistent with autophagic substrate accumulation. The mCherry-GFP-LC3B reporter assay confirmed increased formation of both autophagosomes and autolysosomes, suggesting a defect in autophagic degradation rather than initiation [metz-2018-kctd7-autophagy-abstract].

Additional studies using KCTD7-deficient cells revealed lysosomal acidification defects, altered lysosomal enzymatic composition and activity, drastic lipidomic changes, mTORC1 inactivation, unfolded protein response (UPR) activation with upregulation of ATF4 and CHOP, and increased susceptibility to spermine-induced lysosome-dependent cell death [metz-2018-kctd7-autophagy-abstract]. The UPR activation suggests persistent ER stress, a common feature of many neurodegenerative disorders characterized by misfolded protein accumulation.

Strikingly, the autophagy defect is evolutionarily conserved. Yeast lacking the KCTD7 homolog WHI2 displayed profound defects in autophagy induction and flux during amino acid starvation, with impaired conversion of the LC3 homolog Atg8 [metz-2018-kctd7-autophagy-abstract]. This conservation across more than a billion years of evolution underscores the fundamental importance of KCTD7-like proteins in cellular homeostasis.

Disease Associations: Progressive Myoclonic Epilepsy and Neuronal Ceroid Lipofuscinosis

Biallelic pathogenic variants in KCTD7 cause a severe pediatric neurodegenerative disorder with two overlapping clinical presentations: progressive myoclonic epilepsy type 3 (EPM3, OMIM 611726) and neuronal ceroid lipofuscinosis type 14 (CLN14) [vanbogaert-2007-kctd7-pme-abstract][staropoli-2012-kctd7-cln14-abstract]. Whether these represent distinct entities or a phenotypic spectrum remains debated, but the underlying molecular pathology appears unified.

The disease typically manifests in infancy or early childhood after a period of normal or mildly delayed psychomotor development. The average age of onset is approximately 17 months (range 5-39 months), distinguishing KCTD7-related disease from other progressive myoclonic epilepsies which typically present later [metz-2018-kctd7-autophagy-abstract][jain-2022-kctd7-indian-abstract]. In 60-70% of cases, seizures are the presenting symptom, while other patients first develop movement disorders or developmental regression before seizure onset [metz-2018-kctd7-autophagy-abstract].

Myoclonic seizures are the hallmark, occurring in over 84% of patients, but other seizure types including generalized tonic-clonic, atonic, atypical absence, and focal seizures also occur [jain-2022-kctd7-indian-abstract]. The epilepsy is frequently pharmacoresistant, and neurological deterioration parallels seizure refractoriness [vanbogaert-2007-kctd7-pme-abstract]. Progressive features include cognitive decline with eventual severe dementia, speech deterioration (100% of patients), ataxia (63%), and motor handicap leading to wheelchair dependence. Many patients become non-verbal within years of onset [jain-2022-kctd7-indian-abstract].

Brain MRI is typically normal early in the disease course but may show progressive cerebral and cerebellar atrophy. EEG demonstrates slow dysrhythmia with multifocal and occasionally generalized epileptiform discharges, and photosensitivity is common [vanbogaert-2007-kctd7-pme-abstract]. Notably, retinal degeneration—a characteristic feature of several NCL subtypes—is typically absent or mild in KCTD7-related disease, providing a clinical distinguishing feature from CLN1 disease [metz-2018-kctd7-autophagy-abstract].

To date, over 40 unique pathogenic KCTD7 variants have been identified in more than 60 patients worldwide [jain-2022-kctd7-indian-abstract]. These include missense mutations, small insertions/deletions, splice site variants, and large exonic deletions. Mutations cluster in functionally critical regions: BTB domain mutations typically impair CUL3 binding, while mutations in the C-terminal region (residues 139-289) disrupt substrate (CLN5) interaction [wang-2022-kctd7-cln5-abstract]. Both mutation classes ablate the capacity of KCTD7 to mediate CLN5 degradation, converging on a common pathogenic mechanism.

Mouse Model Evidence and Neurovascular Involvement

The generation of Kctd7 knockout mouse models has provided critical insights into KCTD7 function in vivo and validated its role in neurological disease. Liang et al. (2022) demonstrated that Kctd7-deficient mice develop myoclonic seizures and locomotor defects that closely mirror the human disease phenotype [liang-2022-kctd7-mouse-abstract]. Importantly, these mice exhibit substantial loss of cerebellar Purkinje cells, providing a cellular basis for the progressive ataxia observed in human patients. The cerebellar pathology is accompanied by region-specific defects in brain microvasculature, suggesting that KCTD7 plays a role in neurovascular interactions [liang-2022-kctd7-mouse-abstract].

The connection between KCTD7 and vascular development was initially discovered in the retina, a tractable model system for studying neurovascular interactions. Alevy et al. (2019) identified Kctd7 through a high-throughput screen as a regulator of vascular patterning and subsequently demonstrated that Kctd7 deletion causes defective patterning of the retinal vascular network, including increased branching, vessel length, and lacunarity [alevy-2019-kctd7-retina-abstract]. These alterations reflect early developmental defects, as emergence of both the superficial and deep vascular layers was delayed in Kctd7-null mice. Notably, KCTD7 is expressed in inner retinal neurons (particularly bipolar cells) but is absent from blood vessels themselves, indicating that the vascular phenotype arises from non-cell-autonomous effects of neuronal KCTD7 dysfunction [alevy-2019-kctd7-retina-abstract]. Loss of Kctd7 resulted in increased numbers of bipolar cells during development, suggesting that KCTD7 normally restrains neuronal proliferation or survival in specific contexts.

These mouse model studies collectively establish that KCTD7 is required for proper neuronal survival, excitability, and neurovascular coupling. The finding that Kctd7 deficiency affects both neurons and their associated vasculature suggests that the pathophysiology of KCTD7-related disease may extend beyond cell-autonomous neuronal dysfunction to include aberrant neurovascular interactions that could exacerbate neurodegeneration.

Open Questions

Several important questions regarding KCTD7 function and dysfunction remain unresolved:

1. Complete substrate repertoire: While CLN5 has been identified as a key substrate of CRL3-KCTD7, the full complement of proteins targeted for ubiquitination by this complex remains unknown. Identifying additional substrates could reveal other pathways disrupted in KCTD7 deficiency and potential therapeutic targets.

2. Mechanism of K+ conductance regulation: The precise mechanism by which cytoplasmic KCTD7 influences plasma membrane potassium conductance remains unclear. Whether KCTD7 directly or indirectly regulates specific potassium channel subunits, and which channels are affected, requires further investigation.

3. SAT2 regulation mechanism: How KCTD7 modulates SAT2-mediated glutamine transport is not well understood. It is unclear whether this involves direct protein-protein interaction, post-translational modification of SAT2, or effects on SAT2 trafficking and membrane localization.

4. Phenotypic variability: Despite all patients having loss-of-function KCTD7 mutations, there is clinical heterogeneity in disease severity and progression. The genetic or environmental modifiers responsible for this variability are unknown.

5. Therapeutic approaches: Currently, there are no disease-modifying treatments for KCTD7-related disorders. Understanding whether gene therapy, substrate reduction therapy (reducing CLN5 by other means), or enhancing autophagy could ameliorate disease progression is an important area for future research.

6. Tissue-specific effects: Why neurons are particularly vulnerable to KCTD7 deficiency despite its broad expression pattern is not fully explained. Understanding the unique requirements of neurons for KCTD7 function could provide insights into neuroprotective strategies.

7. Relationship to other NCL genes: KCTD7 dysfunction leads to accumulation of CLN5, which disrupts the CLN6-CLN8 EGRESS complex. How this pathway intersects with other NCL gene products (CLN1, CLN2, CLN3, etc.) and whether there are common therapeutic targets across NCL subtypes warrants investigation.

References

• vanbogaert-2007-kctd7-pme-abstract: Van Bogaert P, Azizieh R, Désir J, Aeby A, De Meirleir L, Laes JF, Christiaens F, Abramowicz MJ. Mutation of a potassium channel-related gene in progressive myoclonic epilepsy. Annals of Neurology 2007; 61(6):579-586. PMID: 17455289. DOI: 10.1002/ana.21121

• azizieh-2011-kctd7-potassium-abstract: Azizieh R, Orduz D, Van Bogaert P, Bouschet T, Rodriguez W, Schiffmann SN, Bharat I, Bharat MJ. Progressive myoclonic epilepsy-associated gene KCTD7 is a regulator of potassium conductance in neurons. Molecular Neurobiology 2011; 44(1):111-121. PMID: 21710140. DOI: 10.1007/s12035-011-8194-0

• kousi-2012-kctd7-mutations-abstract: Kousi M, Anttila V, Schulz A, Calafato S, Jakkula E, Riesch E, Myllykangas L, Kalimo H, Topçu M, Gökben S, Alehan F, Lemke JR, Alber M, Palotie A, Kopra O, Lehesjoki AE. Novel mutations consolidate KCTD7 as a progressive myoclonus epilepsy gene. Journal of Medical Genetics 2012; 49(6):391-399. PMID: 22693283. DOI: 10.1136/jmedgenet-2012-100859

• staropoli-2012-kctd7-cln14-abstract: Staropoli JF, Karaa A, Lim ET, Kirby A, Elbalalesy N, Romansky SG, Leydiker KB, Coppel SH, Barone R, Xin W, MacDonald ME, Abdenur JE, Daly MJ, Sims KB, Cotman SL. A homozygous mutation in KCTD7 links neuronal ceroid lipofuscinosis to the ubiquitin-proteasome system. American Journal of Human Genetics 2012; 91(1):59-71. PMID: 22748208. DOI: 10.1016/j.ajhg.2012.05.023

• moen-2016-kctd7-glutamine-abstract: Moen MN, Fjær R, Hamdani EH, Laerdahl JK, Menchini RJ, Vigeland MD, Sheng Y, Undlien DE, Hassel B, Salih MA, El Khashab HY, Selmer KK, Chaudhry FA. Pathogenic variants in KCTD7 perturb neuronal K+ fluxes and glutamine transport. Brain 2016; 139(12):3109-3120. PMID: 27742667. DOI: 10.1093/brain/aww244

• metz-2018-kctd7-autophagy-abstract: Metz KA, Teng X, et al. KCTD7 deficiency defines a distinct neurodegenerative disorder with a conserved autophagy-lysosome defect. Annals of Neurology 2018; 84(5):766-780. PMID: 30295347. DOI: 10.1002/ana.25351

• wang-2022-kctd7-cln5-abstract: Wang Y, Cao X, Liu P, Zeng W, Peng R, Shi Q, Feng K, Zhang P, Sun H, Wang C, Wang H. KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses. Science Advances 2022; 8(31):eabm5578. PMID: 35921411. PMCID: PMC9348797. DOI: 10.1126/sciadv.abm5578

• jiang-2023-kctd-structure-abstract: Jiang C, Wang R, Kong Z, Zheng D. Structural basis for the ubiquitination of G protein βγ subunits by KCTD5/Cullin3 E3 ligase. Science Advances 2023; 9(29):eadg8369. PMID: 37450587. PMCID: PMC10348674. DOI: 10.1126/sciadv.adg8369. PDB: 8I79

• jain-2022-kctd7-indian-abstract: Jain P, Sharma S, Das B, et al. KCTD7-related progressive myoclonic epilepsy: report of three Indian families and review of literature. Child's Nervous System 2022; 38(5):1009-1020. PMID: 34866617. PMCID: PMC8918358. DOI: 10.1007/s00381-021-05422-4

• alevy-2019-kctd7-retina-abstract: Alevy J, Burger CA, Albrecht NE, Jiang D, Samuel MA. Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function. Neurochemistry International 2019; 129:104486. PMID: 31175897. DOI: 10.1016/j.neuint.2019.104486

• liang-2022-kctd7-mouse-abstract: Liang JH, Alevy J, Akhanov V, Seo R, Massey CA, Jiang D, Zhou J, Sillitoe RV, Noebels JL, Samuel MA. Kctd7 deficiency induces myoclonic seizures associated with Purkinje cell death and microvascular defects. Disease Models & Mechanisms 2022; 15(9):dmm049642. PMID: 35972048. DOI: 10.1242/dmm.049642

• skoblov-2013-kctd-family-abstract: Skoblov M, et al. Protein partners of KCTD proteins provide insights about their functional roles in cell differentiation and vertebrate development. Cell & Bioscience 2013; 3:45. PMID: 24268103. PMCID: PMC3882106. DOI: 10.1186/2045-3701-3-45

• GeneReviews: Metz KA, Bhalerao A, Bhalerao S. KCTD7-Related Progressive Myoclonic Epilepsy. In: Adam MP, et al., editors. GeneReviews. Seattle (WA): University of Washington, Seattle; 2023. https://www.ncbi.nlm.nih.gov/books/NBK619245/

• OMIM 611725: POTASSIUM CHANNEL TETRAMERIZATION DOMAIN-CONTAINING PROTEIN 7; KCTD7. https://www.omim.org/entry/611725

• OMIM 611726: EPILEPSY, PROGRESSIVE MYOCLONIC, 3, WITH OR WITHOUT INTRACELLULAR INCLUSIONS; EPM3. https://omim.org/entry/611726

• UniProt Q96MP8: BTB/POZ domain-containing protein KCTD7. https://www.uniprot.org/uniprotkb/Q96MP8/entry

Citations

1. alevy-2019-kctd7-retina-abstract.md
2. azizieh-2011-kctd7-potassium-abstract.md
3. jain-2022-kctd7-indian-abstract.md
4. jiang-2023-kctd-structure-abstract.md
5. kousi-2012-kctd7-mutations-abstract.md
6. liang-2022-kctd7-mouse-abstract.md
7. metz-2018-kctd7-autophagy-abstract.md
8. metz-2018-kctd7-autophagy-summary.md
9. moen-2016-kctd7-glutamine-abstract.md
10. skoblov-2013-kctd-family-abstract.md
11. staropoli-2012-kctd7-cln14-abstract.md
12. vanbogaert-2007-kctd7-pme-abstract.md
13. vanbogaert-2007-kctd7-pme-summary.md
14. wang-2022-kctd7-cln5-abstract.md
15. wang-2022-kctd7-cln5-summary.md

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Plan summary: We verified identity (KCTD7, UniProt Q96MP8; Homo sapiens; BTB/POZ domain), gathered recent literature including 2023–2024 sources, extracted mechanistic, localization, and disease evidence, and synthesized a comprehensive report with citations and URLs.

Comprehensive research report: KCTD7 (BTB/POZ domain-containing protein KCTD7; UniProt Q96MP8)

Identity verification and domain architecture
- Gene/protein: KCTD7 encodes a soluble protein of ~289 amino acids with an N‑terminal BTB/POZ domain homologous to the T1 tetramerization domain of Kv channels, but it lacks transmembrane segments and is not itself an ion channel. Family context places KCTD7 within the KCTD BTB-domain adaptors that often engage CUL3 E3 ligases. These points are consistently supported by early molecular studies and family reviews (Mol Neurobiol 2011; Cell & Biosci 2013; CNS Neurosci Ther 2019). (azizieh2011progressivemyoclonicepilepsyassociated pages 1-2, liu2013thekctdfamily pages 1-3, teng2019kctdanew pages 4-7, teng2019kctdanew pages 1-2)

Key concepts and definitions (current understanding)
- Molecular role: KCTD7 functions as a BTB/POZ-domain adaptor that binds Cullin3 (CUL3), consistent with the broader KCTD family model in CRL3 ubiquitin ligases. Co-immunoprecipitation shows a KCTD7–CUL3 interaction; pathogenic mutations can abolish this interaction. The KCTD7–CUL3 complex has been visualized by cryo-EM in 2023, consolidating its role as a CUL3 adaptor. (azizieh2011progressivemyoclonicepilepsyassociated pages 1-2, staropoli2012ahomozygousmutation pages 1-2, jiang2023structuralbasisfor pages 1-2)
- Neuronal electrophysiology: Overexpression in neurons hyperpolarizes the membrane and reduces excitability, consistent with a role in modulating K+ conductance. (azizieh2011progressivemyoclonicepilepsyassociated pages 1-2)
- Transport coupling: KCTD7 regulates K+-dependent glutamine transport via the neuronal transporter SAT2 (SLC38A2), linking K+ homeostasis to neurotransmitter precursor supply. (moen2016pathogenicvariantsin pages 1-2)
- Oligomeric state: KCTD family BTB domains commonly form pentamers that dock onto CUL3 in 5:5 assemblies; KCTD7 follows this architectural paradigm based on 2023 cryo-EM evidence. (jiang2023structuralbasisfor pages 1-2)

Protein domains and assembly
- Domains: N‑terminal BTB/POZ domain mediates CUL3 binding and oligomerization; the C‑terminal domain is divergent and expected to confer substrate selectivity, as shown across KCTDs. (liu2013thekctdfamily pages 1-3, teng2019kctdanew pages 4-7)
- Assembly: Structural work across KCTDs shows homopentameric BTB assemblies; cryo-EM demonstrates KCTD7–CUL3 complex formation, consistent with a 5:5 heterodecameric CRL3 architecture. (jiang2023structuralbasisfor pages 1-2)

Subcellular localization
- Wild-type KCTD7 localizes to the plasma membrane and cytoplasm in expression systems and neurons, congruent with roles in ion conductance regulation and substrate adaptor function. (moen2016pathogenicvariantsin pages 1-2)
- Disease variants can mislocalize, forming cytoplasmic aggregates and showing reduced membrane trafficking; variants also disrupt CUL3 binding. (staropoli2012ahomozygousmutation pages 1-2, ladha2014potentialrolefor pages 18-23)

Pathways and processes
- Ubiquitin–proteasome system (UPS): KCTD7 is part of CRL3-type E3 ligase assemblies via its BTB domain. Disease-associated mutations that disrupt CUL3 interaction implicate UPS dysfunction in pathogenesis. (staropoli2012ahomozygousmutation pages 1-2, liu2013thekctdfamily pages 1-3)
- Ion/glutamine homeostasis: KCTD7 modulates K+ flux in neurons and couples this to glutamine uptake via SAT2, impacting neurotransmitter metabolism. (moen2016pathogenicvariantsin pages 1-2)
- Autophagy–lysosome axis: Reviews and family context note an emerging link of KCTD7 deficiency to autophagy–lysosome dysfunction in neurodegeneration; this is consistent with the NCL phenotype and broader KCTD literature, although direct substrates remain unidentified. (vergara2025substrateidentificationanda pages 11-16)
- GPCR/G protein signaling: While several KCTDs modulate GPCR/Gβγ signaling as CRL3 adaptors, the 2023 cryo-EM work places KCTD7 structurally within this pentameric CRL3 paradigm; direct KCTD7 substrates in GPCR pathways have not yet been defined. (jiang2023structuralbasisfor pages 1-2)

Disease associations, genotype–phenotype, and model data
- Primary disease: Biallelic KCTD7 variants cause early-onset progressive myoclonic epilepsy (PME) and can present as neuronal ceroid lipofuscinosis subtype CLN14 in some families. Onset typically 8–20 months with refractory myoclonic seizures, regression, ataxia, and in some cases vision loss. (staropoli2012ahomozygousmutation pages 1-2, azizieh2011progressivemyoclonicepilepsyassociated pages 1-2)
- Mechanistic genetics: The pathogenic Arg184Cys variant abrogates CUL3 binding and alters KCTD7 localization, linking UPS disruption to disease. Additional missense, nonsense, frameshift, and deletion variants show variable effects on membrane trafficking, K+ conductance, and SAT2 activity. (staropoli2012ahomozygousmutation pages 1-2, moen2016pathogenicvariantsin pages 1-2)
- Quantitative data: The literature up to 2023 catalogs >40 unique KCTD7 mutations in patients with PME/CLN14; variants are typically autosomal recessive with unaffected heterozygous carriers. (jiang2023structuralbasisfor pages 1-2, teng2019kctdanew pages 4-7)
- Physiology/biomarkers: Patient data include altered CSF amino acids (decreased glutamate, increased glutamine) consistent with impaired glutamine cycling; seizures are therapy-resistant. (moen2016pathogenicvariantsin pages 1-2)

Recent developments and latest research (2023–2024)
- Cryo-EM: Jiang et al. (Science Advances, 2023) solved structures of KCTD5–Gβγ and reported a KCTD7–CUL3 complex, establishing a pentameric architecture for KCTD E3 ligases and providing a structural basis to interpret pathogenic KCTD7 variants. This supports the model that KCTD7 is a CRL3 adaptor even if its physiological substrate(s) remain unknown. URL: https://doi.org/10.1126/sciadv.adg8369 (published July 2023). (jiang2023structuralbasisfor pages 1-2)
- BTB/POZ domain reviews (2024): Recent reviews synthesize atypical BTB architectures and CRL3 regulation and note that KCTD7 deficiency defines a distinct neurodegenerative disorder, aligning with autophagy–lysosome pathway involvement and UPS defects. (vergara2025substrateidentificationanda pages 11-16)

Current applications and real-world implementations
- Diagnostics: Genetic testing panels for PME/NCL increasingly include KCTD7; identification of biallelic pathogenic variants informs prognosis and counseling, especially for early-onset, refractory myoclonus with regression. (staropoli2012ahomozygousmutation pages 1-2, moen2016pathogenicvariantsin pages 1-2)
- Mechanistic modeling: Structural data now enable in silico mapping of patient variants onto the KCTD7–CUL3 interface to predict loss of function and prioritize variants of uncertain significance for functional testing. (jiang2023structuralbasisfor pages 1-2)
- Biomarker hypotheses: CSF amino acid profiles and imaging of lysosomal storage changes (in NCL presentations) may complement genetics in patient stratification, although standardized clinical deployment requires further study. (moen2016pathogenicvariantsin pages 1-2, staropoli2012ahomozygousmutation pages 1-2)

Expert opinions and analysis
- Consensus across authoritative sources is that KCTD7 is a neuronal CUL3 adaptor with roles coupling ion conductance and amino acid transport; loss of function disrupts UPS and membrane trafficking, producing hyperexcitability and neurodegeneration. The field’s key knowledge gaps include identification of direct KCTD7 substrates in neurons and mechanistic integration with autophagy–lysosome and GPCR signaling modules highlighted for other KCTDs. (liu2013thekctdfamily pages 1-3, teng2019kctdanew pages 4-7, jiang2023structuralbasisfor pages 1-2, vergara2025substrateidentificationanda pages 11-16)

Relevant statistics and data from recent studies
- Electrophysiology: Overexpressed KCTD7 hyperpolarizes neurons and reduces excitability; pathogenic variants reverse these effects (Molecular Neurobiol. 2011). (azizieh2011progressivemyoclonicepilepsyassociated pages 1-2)
- Transport: Wild-type KCTD7 enhances SAT2-mediated glutamine uptake in a K+-dependent fashion; disease variants abolish this regulation (Brain 2016). (moen2016pathogenicvariantsin pages 1-2)
- Genetics: One family’s Arg184Cys homozygous variant segregated with severe infantile-onset NCL/PME; functional assays showed lost CUL3 binding and altered localization (AJHG 2012). (staropoli2012ahomozygousmutation pages 1-2)
- Variant burden: Reviews and 2023 structural work cite >40 unique patient mutations mapped across BTB and C-terminal regions, consistent with autosomal recessive inheritance and loss-of-function mechanisms. (jiang2023structuralbasisfor pages 1-2, teng2019kctdanew pages 4-7)

References with URLs and dates
- Azizieh R et al. Progressive Myoclonic Epilepsy‑Associated Gene KCTD7 is a Regulator of Potassium Conductance in Neurons. Molecular Neurobiology. 2011 Jun;44:111–121. https://doi.org/10.1007/s12035-011-8194-0 (azizieh2011progressivemyoclonicepilepsyassociated pages 1-2)
- Staropoli JF et al. A homozygous mutation in KCTD7 links neuronal ceroid lipofuscinosis to the ubiquitin‑proteasome system. American Journal of Human Genetics. 2012 Jul;91(1):202–208. https://doi.org/10.1016/j.ajhg.2012.05.023 (staropoli2012ahomozygousmutation pages 1-2)
- Moen MN et al. Pathogenic variants in KCTD7 perturb neuronal K+ fluxes and glutamine transport. Brain. 2016 Dec;139(Pt 12):3109–3120. https://doi.org/10.1093/brain/aww244 (moen2016pathogenicvariantsin pages 1-2)
- Liu Z et al. The KCTD family of proteins: structure, function, disease relevance. Cell & Bioscience. 2013 Nov;3:45. https://doi.org/10.1186/2045-3701-3-45 (liu2013thekctdfamily pages 1-3)
- Teng X et al. KCTD: A new gene family involved in neurodevelopmental and neuropsychiatric disorders. CNS Neuroscience & Therapeutics. 2019 Jun;25:887–902. https://doi.org/10.1111/cns.13156 (teng2019kctdanew pages 4-7, teng2019kctdanew pages 1-2)
- Jiang W et al. Structural basis for the ubiquitination of G protein βγ subunits by KCTD5/Cullin3 E3 ligase (includes KCTD7–CUL3 complex). Science Advances. 2023 Jul;9:e adg8369. https://doi.org/10.1126/sciadv.adg8369 (jiang2023structuralbasisfor pages 1-2)
- Walma DAC. Structure and function of atypical BTB domains in health and disease. 2024. [Review; journal details not specified in excerpt]. (vergara2025substrateidentificationanda pages 11-16)

Limitations and open questions
- Direct neuronal substrates of KCTD7-CRL3 are not yet identified; thus, the precise signaling pathway(s) downstream of KCTD7 remain to be delineated.
- Autophagy–lysosome involvement is suggested by disease phenotype and family reviews but requires KCTD7‑specific mechanistic studies.
- The extent to which KCTD7 interfaces with GPCR signaling, as shown for other KCTDs, remains to be established in vivo. (jiang2023structuralbasisfor pages 1-2, vergara2025substrateidentificationanda pages 11-16)

References

1. (azizieh2011progressivemyoclonicepilepsyassociated pages 1-2): Régis Azizieh, David Orduz, Patrick Van Bogaert, Tristan Bouschet, Wendy Rodriguez, Serge N. Schiffmann, Isabelle Pirson, and Marc J. Abramowicz. Progressive myoclonic epilepsy-associated gene kctd7 is a regulator of potassium conductance in neurons. Molecular Neurobiology, 44:111-121, Jun 2011. URL: https://doi.org/10.1007/s12035-011-8194-0, doi:10.1007/s12035-011-8194-0. This article has 90 citations and is from a peer-reviewed journal.

2. (liu2013thekctdfamily pages 1-3): Zhepeng Liu, Yaqian Xiang, and Guihong Sun. The kctd family of proteins: structure, function, disease relevance. Cell & Bioscience, 3:45-45, Nov 2013. URL: https://doi.org/10.1186/2045-3701-3-45, doi:10.1186/2045-3701-3-45. This article has 158 citations and is from a peer-reviewed journal.

3. (teng2019kctdanew pages 4-7): Xinchen Teng, Abdel Aouacheria, Loïc Lionnard, Kyle A. Metz, Lucian Soane, Atsushi Kamiya, and J. Marie Hardwick. Kctd: a new gene family involved in neurodevelopmental and neuropsychiatric disorders. CNS Neuroscience & Therapeutics, 25:887-902, Jun 2019. URL: https://doi.org/10.1111/cns.13156, doi:10.1111/cns.13156. This article has 130 citations and is from a peer-reviewed journal.

4. (teng2019kctdanew pages 1-2): Xinchen Teng, Abdel Aouacheria, Loïc Lionnard, Kyle A. Metz, Lucian Soane, Atsushi Kamiya, and J. Marie Hardwick. Kctd: a new gene family involved in neurodevelopmental and neuropsychiatric disorders. CNS Neuroscience & Therapeutics, 25:887-902, Jun 2019. URL: https://doi.org/10.1111/cns.13156, doi:10.1111/cns.13156. This article has 130 citations and is from a peer-reviewed journal.

5. (staropoli2012ahomozygousmutation pages 1-2): John F. Staropoli, Amel Karaa, Elaine T. Lim, Andrew Kirby, Naser Elbalalesy, Stephen G. Romansky, Karen B. Leydiker, Scott H. Coppel, Rosemary Barone, Winnie Xin, Marcy E. MacDonald, Jose E. Abdenur, Mark J. Daly, Katherine B. Sims, and Susan L. Cotman. A homozygous mutation in kctd7 links neuronal ceroid lipofuscinosis to the ubiquitin-proteasome system. American journal of human genetics, 91 1:202-8, Jul 2012. URL: https://doi.org/10.1016/j.ajhg.2012.05.023, doi:10.1016/j.ajhg.2012.05.023. This article has 147 citations and is from a highest quality peer-reviewed journal.

6. (jiang2023structuralbasisfor pages 1-2): Wentong Jiang, Wei Wang, Yinfei Kong, and Sanduo Zheng. Structural basis for the ubiquitination of g protein βγ subunits by kctd5/cullin3 e3 ligase. Science Advances, Jul 2023. URL: https://doi.org/10.1126/sciadv.adg8369, doi:10.1126/sciadv.adg8369. This article has 22 citations and is from a highest quality peer-reviewed journal.

7. (moen2016pathogenicvariantsin pages 1-2): Marivi Nabong Moen, Roar Fjær, El Hassan Hamdani, Jon K. Laerdahl, Robin Johansen Menchini, Magnus Dehli Vigeland, Ying Sheng, Dag Erik Undlien, Bjørnar Hassel, Mustafa A. Salih, Heba Y. El Khashab, Kaja Kristine Selmer, and Farrukh Abbas Chaudhry. Pathogenic variants in kctd7 perturb neuronal k+ fluxes and glutamine transport. Brain : a journal of neurology, 139 Pt 12:3109-3120, Dec 2016. URL: https://doi.org/10.1093/brain/aww244, doi:10.1093/brain/aww244. This article has 46 citations.

8. (ladha2014potentialrolefor pages 18-23): FA Ladha. Potential role for human kctd9 in the autophagy pathway: a novel autophagosome-associated protein. Unknown journal, 2014.

9. (vergara2025substrateidentificationanda pages 11-16): R Lobato Vergara. Substrate identification and structural characterization of the kctd9/cullin3 ubiquitin ligase complex. Unknown journal, 2025.

Citations

1. azizieh2011progressivemyoclonicepilepsyassociated pages 1-2
2. moen2016pathogenicvariantsin pages 1-2
3. jiang2023structuralbasisfor pages 1-2
4. vergara2025substrateidentificationanda pages 11-16
5. staropoli2012ahomozygousmutation pages 1-2
6. liu2013thekctdfamily pages 1-3
7. teng2019kctdanew pages 4-7
8. teng2019kctdanew pages 1-2
9. ladha2014potentialrolefor pages 18-23
10. Review; journal details not specified in excerpt
11. https://doi.org/10.1126/sciadv.adg8369
12. https://doi.org/10.1007/s12035-011-8194-0
13. https://doi.org/10.1016/j.ajhg.2012.05.023
14. https://doi.org/10.1093/brain/aww244
15. https://doi.org/10.1186/2045-3701-3-45
16. https://doi.org/10.1111/cns.13156
17. https://doi.org/10.1007/s12035-011-8194-0,
18. https://doi.org/10.1186/2045-3701-3-45,
19. https://doi.org/10.1111/cns.13156,
20. https://doi.org/10.1016/j.ajhg.2012.05.023,
21. https://doi.org/10.1126/sciadv.adg8369,
22. https://doi.org/10.1093/brain/aww244,

Functional Annotation of KCTD7 (BTB/POZ Domain-Containing Protein KCTD7) in Human

Gene Identity and Key Characteristics

KCTD7 (Potassium Channel Tetramerization Domain-containing protein 7) is a human protein encoded by the KCTD7 gene (UniProt Q96MP8). Despite its name, KCTD7 is not an ion channel itself, but was named for a conserved N-terminal domain homologous to the T1 tetramerization domain of Kv potassium channels (pubmed.ncbi.nlm.nih.gov). This N-terminal region is a BTB/POZ domain – a ~120-amino-acid Broad-Complex/Tramtrack/Bric-à-brac motif – which mediates protein-protein interactions and homo-oligomerization (pmc.ncbi.nlm.nih.gov). The human genome encodes 26 KCTD family members sharing this structural motif (pmc.ncbi.nlm.nih.gov). KCTD7 is one of these BTB-domain proteins, originally of unknown function but implicated in a rare pediatric epilepsy syndrome (pmc.ncbi.nlm.nih.gov). It was first identified in 2007 when KCTD7 mutations were found to cause progressive myoclonic epilepsy type 3 (EPM3), a severe early-onset epilepsy with neurodegeneration (pmc.ncbi.nlm.nih.gov). Pathogenic variants in KCTD7 also lead to neuronal ceroid lipofuscinosis 14 (CLN14) – a form of Batten disease – and have been reported in opsoclonus-myoclonus ataxia syndrome, underscoring the gene’s clinical significance (pmc.ncbi.nlm.nih.gov). In summary, KCTD7 is a BTB-domain adapter protein whose loss of function causes infantile-onset epilepsy and neurodegenerative disease, suggesting it plays an essential role in neuronal physiology.

Expression and Subcellular Localization

KCTD7 is predominantly a neuronal protein, expressed broadly in the central nervous system. Initial studies in mice showed high expression in the cerebellar Purkinje cells, hippocampus, and cortical neurons (www.ncbi.nlm.nih.gov). Human transcriptome data indicate KCTD7 is expressed in many tissues but is enriched in the brain and retina, fitting with its neuron-specific functions (www.proteinatlas.org) (www.proteinatlas.org). In fact, KCTD7 mRNA is classified as “tissue-enhanced” in retina and brain, clustering with genes involved in neuronal signaling (www.proteinatlas.org) (www.proteinatlas.org). Within cells, KCTD7 is localized to the cytosol. Confocal microscopy reveals KCTD7 has a diffuse cytosolic distribution, and it co-localizes with its binding partners in the cytoplasm (pmc.ncbi.nlm.nih.gov). Biochemical fractionation confirms that both KCTD7 and its known substrates are highly enriched in the cytosolic fraction, with little presence in membrane or nuclear compartments (pmc.ncbi.nlm.nih.gov). (Notably, one study reported a minor membrane association for a mutant substrate, as discussed below, but wild-type KCTD7 itself is mainly intracellular cytosolic (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).) This subcellular localization aligns with KCTD7’s role as a cytosolic regulatory protein, rather than a membrane-spanning receptor or channel. In summary, KCTD7 is expressed postnatally in neurons of the CNS (and to a lesser extent in other tissues) and functions primarily in the cytosolic compartment of the cell (www.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Molecular Function: Cullin-3 E3 Ubiquitin Ligase Adaptor

Current Understanding: KCTD7’s primary molecular function is as an adaptor protein for a Cullin-3 (CUL3) E3 ubiquitin ligase complex. Like many BTB-domain proteins, KCTD7 can bind CUL3 and recruit specific substrate proteins for ubiquitination (pmc.ncbi.nlm.nih.gov). Early evidence of this came from Azizieh et al. (2011), who showed that KCTD7 physically interacts with CUL3 in co-immunoprecipitation assays (pubmed.ncbi.nlm.nih.gov). This suggested KCTD7 might function analogously to other BTB-containing ubiquitin ligase adaptors (e.g. KLHL family proteins), even before its substrates were known. Indeed, the BTB/POZ domain in KCTD7 is required for CUL3 binding (pmc.ncbi.nlm.nih.gov), and disease-causing mutations in KCTD7 disrupt the KCTD7–CUL3 interaction (pmc.ncbi.nlm.nih.gov). Once bound to CUL3, KCTD7 forms a Cullin-3 RING ligase (CRL3) complex together with the Rbx1 RING-finger protein (which recruits a ubiquitin-conjugating enzyme) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In this complex, KCTD7 serves as the substrate-recognition subunit (the “adapter”) that confers target specificity (pmc.ncbi.nlm.nih.gov). Until recently, the identity of KCTD7’s target substrates was unclear, and the protein’s function was “uncharacterized” in molecular terms (pmc.ncbi.nlm.nih.gov). However, breakthrough studies in 2022–2023 have identified two key substrate pathways of KCTD7’s CRL3 complex: one involving calpain proteases and another involving a lysosomal trafficking protein CLN5.

• Regulation of Calpain Proteases: In 2023, Sharma et al. discovered that KCTD7 targets the ubiquitous calcium-dependent proteases calpain-1 (CAPN1) and calpain-2 (CAPN2) for atypical, non-degradative ubiquitination (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Normally, calpains are cysteine proteases that cleave various substrates and are tightly regulated in cells (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The KCTD7–CUL3 complex was found to bind directly to calpain-1 and -2 (via the calpain domain III) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov) and attach multi-ubiquitin chains on specific lysine residues of the calpains (lysine-398 on calpain-1, and lysines-280/674 on calpain-2) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These chains were “atypical” ubiquitin linkages (mainly K6-, K27-, K29-, and K63-linked chains rather than the canonical K48 proteasomal tag) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Importantly, adding these ubiquitin chains did not lead to calpain degradation – consistent with no change in calpain levels upon KCTD7 manipulation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov) – but instead suppressed calpain activity (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Mechanistically, ubiquitination of calpain reduced its enzymatic activity and altered its localization: mutant calpain-1 that cannot be ubiquitinated (K398R) showed abnormally increased binding to its stabilizing subunit (CAPNS1) and mislocalized more to the plasma membrane, resulting in hyperactivation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). By ubiquitinating calpains, KCTD7 keeps these proteases largely cytosolic and in a restrained state (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This negative regulation of calpain is a novel function – it effectively tethers and inactivates calpains via ubiquitin signals rather than destroying them. Loss of KCTD7 leads to unchecked calpain activity (see Biological Processes below), which has dire consequences for neurons (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This recent finding “unveils a novel mechanism” for controlling calpains and positions KCTD7 as a critical regulator of protease signaling (pmc.ncbi.nlm.nih.gov).

• Regulation of Lysosomal Protein (CLN5): In 2022, Wang et al. reported another KCTD7 target that illuminates the lysosomal storage aspect of KCTD7-deficient disease (pmc.ncbi.nlm.nih.gov). They found that the CRL3–KCTD7 complex targets the lysosomal protein CLN5 for ubiquitin-mediated degradation* (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). *CLN5 is a glycoprotein required for lysosomal enzyme trafficking, and mutations in CLN5 cause a form of Batten disease. In KCTD7’s normal function, it binds and ubiquitinates CLN5, marking it for proteasomal turnover (pmc.ncbi.nlm.nih.gov). In cells lacking functional KCTD7, CLN5 accumulates to abnormally high levels, and this excess CLN5 disrupts lysosomal enzyme trafficking (pmc.ncbi.nlm.nih.gov). Specifically, the accumulated CLN5 was shown to interfere with the interactions of CLN6/CLN8 (ER proteins) with lysosomal hydrolases in the endoplasmic reticulum, thereby blocking ER-to-Golgi transport of multiple lysosomal enzymes (pmc.ncbi.nlm.nih.gov). The result is a broad lysosomal dysfunction with reduced delivery of enzymes to lysosomes and consequent buildup of undegraded substrates (manifesting as ceroid lipofuscin storage in neurons) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This work revealed “previously unrecognized roles of KCTD7-mediated CLN5 proteolysis in lysosomal homeostasis” (pmc.ncbi.nlm.nih.gov). In essence, KCTD7 normally acts to degrade CLN5 at the proper time, preventing CLN5 from reaching excessive levels that would perturb the lysosomal system (pmc.ncbi.nlm.nih.gov). The 2022 study also noted that disease-causing mutations in KCTD7 often disrupt the KCTD7–CUL3 interaction or the KCTD7–CLN5 binding, thus impairing ubiquitination of CLN5 and leading to its pathological accumulation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Together with the calpain findings, this identifies KCTD7 as a multi-functional adaptor: it can assemble distinct CRL3 complexes to modulate both protease activity (calpains) and protein turnover (lysosomal enzymes) depending on the substrate. These molecular functions explain how KCTD7 loss derails cellular homeostasis on multiple fronts.

Biological Processes and Pathways Involving KCTD7

Through the above molecular interactions, KCTD7 is involved in several critical biological processes:

• Regulation of Neuronal Excitability: A hallmark of KCTD7’s function is its impact on neuronal resting membrane potential and excitability. Loss-of-function mutations in KCTD7 lead to neuronal hyperexcitability and seizures, whereas KCTD7 overexpression causes hypo-excitability. In patch-clamp studies on cultured neurons, introducing KCTD7 was found to hyperpolarize the cell’s resting membrane potential and reduce firing frequency (pubmed.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). Conversely, neurons lacking KCTD7 (or from KCTD7-deficient mice) show a depolarized resting potential and increased propensity for spontaneous firing and seizures (www.ncbi.nlm.nih.gov). This effect was demonstrated by Van Bogaert et al. and Azizieh et al.: patient-derived KCTD7 nonsense mutations resulted in depolarized neuronal membranes, while wild-type KCTD7 transfection drove a more negative resting potential (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). The mechanism underlying this electrophysiological effect appears to be indirect via KCTD7’s control of calpain. Calpain hyperactivity can cleave neuronal ion channels and synaptic proteins, potentially leading to altered ion currents. For example, excessive calpain activity is known to cleave the K-Cl cotransporter KCC2 and other regulators of inhibitory signaling, which can make GABAergic currents depolarizing (pmc.ncbi.nlm.nih.gov). Although the exact substrates in KCTD7-deficient neurons remain under investigation, the current model is that KCTD7 restrains calpains to maintain ion channel and receptor integrity, thereby stabilizing the resting membrane potential. In KCTD7’s absence, calpains likely aberrantly cleave key ion channel subunits or scaffold proteins, resulting in reduced potassium conductance and neuronal depolarization (pubmed.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov). Supporting this, KCTD7 was originally described as a “regulator of potassium conductance in neurons” based on its hyperpolarizing effect (www.jle.com). Thus, KCTD7 is intimately involved in neuronal excitability pathways – not by acting as a channel itself, but by safeguarding the components (channels, transporters, etc.) that determine neuronal resting potential and firing thresholds.

• Ubiquitin-Proteasome and Protein Quality Control Pathways: As an adaptor for a ubiquitin ligase, KCTD7 is part of the ubiquitin-proteasome system (UPS). It guides the CRL3 E3 ligase to specific targets, thereby influencing protein stability and signaling. One relevant pathway is the antigen processing and MHC class I presentation pathway, where ubiquitination plays a key role in generating peptides – indeed, pathway databases list KCTD7 among proteins in ubiquitination modules of antigen presentation (www.genecards.org). More directly, KCTD7-mediated ubiquitination of CLN5 ties it into the lysosome–autophagy pathway: by regulating lysosomal enzyme trafficking, KCTD7 affects cellular degradative capacity and proteostasis (pmc.ncbi.nlm.nih.gov). In KCTD7-deficient cells, lysosomal catabolic function is impaired (due to misrouting of enzymes), linking KCTD7 to lysosomal storage disease mechanisms (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This places KCTD7 at the crossroads of UPS and lysosomal degradation pathways – two major proteolytic systems in cells. Additionally, KCTD7’s control of calpains represents involvement in a non-lysosomal protease pathway: calpains are calcium-activated proteases that modulate cytoskeletal dynamics, cell death, synaptic plasticity, and other processes (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). By restraining calpain activity, KCTD7 indirectly influences these downstream pathways. For instance, calpain hyperactivation can trigger apoptotic cascades; in KCTD7 knockout neurons, unchecked calpain led to excessive cleavage of α-spectrin (a cytoskeletal protein) and activation of caspase-3, a hallmark of apoptosis (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Therefore, KCTD7 participates in cell survival pathways, preventing aberrant protease activation that would otherwise damage the cytoskeleton and activate cell death programs. In summary, KCTD7 links to multiple biochemical pathways: it is a component of the Cullin–RING ubiquitin ligase network, it upholds lysosomal function by regulating enzyme trafficking, and it modulates calcium-dependent signaling through calpain control. These combined actions maintain neuronal health by balancing protein turnover and proteolysis.

• Neurodevelopment and Neurovascular Interactions: Emerging evidence suggests KCTD7 also plays a role in neurodevelopmental processes, likely as a downstream consequence of its core functions. A 2019 study examined KCTD7 in mouse retinal development – an accessible CNS model – and found that Kctd7 knockout mice have defects in retinal neuron populations and blood vessel patterning (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Notably, Kctd7⁻/⁻ mice showed ~30% increases in abnormal branching of retinal vasculature in deep layers, along with significantly altered vessel density (pmc.ncbi.nlm.nih.gov). These vascular defects were traced to neuronal causes: KCTD7 is expressed in inner retinal neurons (but not in vessels), and loss of KCTD7 led to an excess of certain interneurons (bipolar cells) during development, which in turn dysregulated angiogenic cues (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). By postnatal day 8, Kctd7⁻/⁻ retinas had ~21% more bipolar cells than normal, correlating with delayed and disorganized vessel layer formation (pmc.ncbi.nlm.nih.gov). Functional consequences were seen in the electroretinogram: Kctd7⁻/⁻ mice had ~30–40% reduced retinal responses (a- and b-wave amplitudes), indicating impaired retinal circuit function (pmc.ncbi.nlm.nih.gov). This study highlights that neuronal KCTD7 influences neurovascular development, potentially through regulating proteostasis in developing neurons that secrete angiogenic factors. While the precise molecular mechanism wasn’t fully resolved, the authors suggest it may involve KCTD7-regulated neurovascular signaling – an example of how KCTD7’s cellular role (protease regulation) can have broader tissue-level effects (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These findings align with the human phenotype: children with KCTD7 mutations often experience developmental regression and neurological decline, hinting that KCTD7 is required for normal neural network maturation. Thus, beyond its immediate biochemical pathways, KCTD7 contributes to higher-order biological processes like synaptic development and neuron–glia–vascular interactions necessary for healthy brain function (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Clinical Significance and Current Developments

Disease Association: Mutations in KCTD7 cause KCTD7-related Progressive Myoclonic Epilepsy (PME), also designated EPM3, which typically begins in infancy. A review of reported cases shows onset of neurological symptoms (myoclonic seizures often being the first sign) between about 5 months and 3 years of age (www.ncbi.nlm.nih.gov). Affected infants develop frequent, refractory seizures (myoclonic and generalized types) and progressive neurocognitive decline. Importantly, many patients also exhibit features of a lysosomal storage disorder: some have intracellular inclusions of lipofuscin in tissues, linking this condition to neuronal ceroid lipofuscinosis (now classified as CLN14 in the NCL disease spectrum) (pmc.ncbi.nlm.nih.gov). Pathogenic variants in KCTD7 are usually biallelic loss-of-function (e.g. nonsense, frameshift, or missense disrupting the BTB domain). For example, the first family described had a homozygous nonsense mutation (p.R184) (www.jle.com), and subsequent studies identified various missense mutations that abolish either CUL3 binding or substrate interaction (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). By 2012, at least a half-dozen distinct KCTD7 mutations were reported across unrelated PME families worldwide (www.jle.com) (www.jle.com), and more have been discovered since (including compound heterozygous cases in diverse ethnic backgrounds (www.jle.com)). Genetic testing for KCTD7 mutations is now part of the diagnostic workup for early-onset progressive myoclonic epilepsies (www.ncbi.nlm.nih.gov), and a 2025 review noted that KCTD7* mutations account for a small but significant subset of PME cases globally (www.ncbi.nlm.nih.gov).

Pathogenic Mechanism: The convergence of recent research has largely clarified how KCTD7 loss leads to disease. The two major pathogenic mechanisms are calpain hyperactivation and lysosomal dysfunction, as described above. In KCTD7-deficient neurons, calpain activity is abnormally high, resulting in excessive cleavage of neuronal substrates and synaptic proteins (pmc.ncbi.nlm.nih.gov). This likely causes synaptic deterioration, altered ion channel function, and activation of cell death pathways (caspase-3 mediated apoptosis), which together produce epilepsy and neurodegeneration (pmc.ncbi.nlm.nih.gov). At the same time, accumulation of CLN5 and mis-trafficking of lysosomal enzymes lead to lysosomal storage and impaired waste clearance in neurons (pmc.ncbi.nlm.nih.gov). This combination – excitotoxicity from protease overactivity and toxic buildup from lysosomal failure – explains the rapid neurodegeneration seen in patients. Notably, mouse models of KCTD7 deficiency closely mirror the human disease: Kctd7⁻/⁻ mice develop ataxia, motor impairment, and progressive neurodegeneration (for instance, they show significant Purkinje cell loss in the cerebellum accompanied by activated caspase-3 and gliosis) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These mice also exhibit spontaneous seizures and shortened lifespans, validating the causal role of KCTD7 loss in epilepsy. Importantly, when Kctd7-knockout mice were treated with a calpain inhibitor, their neurodegenerative phenotypes were largely rescued (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Sharma et al. (2023) administered the broad-spectrum calpain inhibitor E-64 to Kctd7⁻/⁻ mice starting at weaning, and over 5 weeks this treatment significantly prevented the usual decline: the Kctd7 knockout mice on E-64 showed preserved motor function and much less neuronal death compared to untreated knockouts (pmc.ncbi.nlm.nih.gov). This striking result demonstrates that calpain hyperactivation is a major driver of pathology in KCTD7-related disease, and that it can be ameliorated by therapeutically targeting calpains (pmc.ncbi.nlm.nih.gov). It also proves the principle that the molecular discoveries have direct translational potential.

Current and Future Applications: While there is currently no cure for KCTD7-PME/CLN14, these new insights suggest potential interventions. One avenue is the use of calpain inhibitors as a therapeutic strategy. Some calpain inhibitors (such as MDL-28170 and others) have shown neuroprotective effects in preclinical models of neurodegeneration (pmc.ncbi.nlm.nih.gov). In fact, selective calpain inhibitors are in early clinical trials for conditions like Alzheimer’s disease (pmc.ncbi.nlm.nih.gov), given calpain’s role in neurodegenerative pathways. For KCTD7-deficient patients, calpain inhibition could conceivably reduce neuronal damage and slow disease progression – a hypothesis supported by the mouse rescue experiments (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Another application is in diagnostics and counseling: recognizing that KCTD7 mutations cause a syndrome that overlaps epilepsy and Batten disease has led to broader genetic screening. Children presenting with unexplained early epilepsy and developmental regression are now often tested for KCTD7 among other genes (www.ncbi.nlm.nih.gov). Early diagnosis can inform supportive care (seizure management, physical therapy, low-vision interventions if applicable) and allow family planning via carrier testing (www.ncbi.nlm.nih.gov). From a research standpoint, KCTD7 is now a promising target to study neurodegeneration mechanisms. Its dual control of calpains and lysosomal function links two key pathological processes. Experts have noted that calpain hyperactivity contributes to common disorders such as type II diabetes, muscular dystrophy, and neurodegenerative diseases like Parkinson’s and Alzheimer’s (pmc.ncbi.nlm.nih.gov). Thus, understanding the KCTD7–calpain regulatory axis could yield insight into those diseases as well. The discovery of KCTD7’s role as a calpain “brake” is particularly significant – as one 2023 paper emphasized, these results reveal “a novel mechanism and potential target to restrain calpain activity in human disease” (pmc.ncbi.nlm.nih.gov). In a broader sense, KCTD7 exemplifies how a once-mysterious protein can be functionally annotated through modern techniques (tandem affinity purification, CRISPR knockouts, cryo-EM structures (pdbj.org)) to uncover its interactome and role. The cryo-EM structure of the KCTD7–CUL3 complex (solved in 2023) now provides a blueprint at atomic resolution for how KCTD7 assembles with CUL3 (pdbj.org). This structural knowledge could guide drug discovery – for instance, screening for small molecules that enhance or mimic KCTD7’s binding to calpain, effectively substituting its function in patients with loss-of-function mutations. In summary, current research is not only deepening our understanding of KCTD7’s function but is actively suggesting therapeutic angles, from repurposing calpain inhibitors to potentially stabilizing the mutant KCTD7–CUL3 complex, all of which offer hope for addressing the devastating disorder caused by KCTD7 mutations.

Expert Commentary

Authoritative sources highlight the importance of KCTD7 in maintaining neuronal homeostasis. A 2025 clinical review notes that KCTD7 is expressed widely in the CNS and that its loss leads to an “inherited defect of the neuron plasma membrane’s resting potential”, linking this to the observed seizures (www.ncbi.nlm.nih.gov). This underscores that KCTD7’s effect on excitability is a primary feature of the disease. In a 2022 Science Advances article, researchers remarked that their findings “reveal previously unrecognized roles of KCTD7-mediated [protein] proteolysis in lysosomal homeostasis” and that KCTD7 and its substrate CLN5 “function in a common neurodegenerative pathway.” (pmc.ncbi.nlm.nih.gov). This expert analysis places KCTD7 as a key node in the network of proteins that, when disrupted, lead to neurodegeneration. Likewise, the 2023 study by Sharma et al. concluded that “these results unveil a novel mechanism … to restrain calpain activity in human disease and shed light on the molecular pathogenesis of KCTD7-associated disease.” (pmc.ncbi.nlm.nih.gov). Leading epilepsy researchers (e.g. Minassian et al., 2016) have pointed out that KCTD7 firmly belongs in the PME gene catalog alongside ion-channel genes, even though KCTD7 itself is not an ion channel – an insight that only makes sense now that we know it regulates ion channel-modulating proteases (www.jle.com) (www.ncbi.nlm.nih.gov). In summary, experts consider KCTD7 a crucial regulator of neuronal stability, whose absence triggers a cascade of proteostatic and excitability disturbances. The recent elucidation of its molecular function has been hailed as an important step toward understanding and eventually treating the severe epilepsy and neurodegeneration seen in KCTD7 deficiency (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

In conclusion, KCTD7 is a BTB-domain adaptor protein that plays a vital role in neurons by assembling a Cullin-3 ubiquitin ligase complex to ubiquitinate specific targets. It protects neurons from hyperexcitability and degeneration by (1) dampening calpain protease activity through non-degradative ubiquitination, and (2) promoting lysosomal protein turnover (e.g. degrading CLN5) to ensure proper enzyme trafficking. Its loss leads to a combination of uncontrolled proteolysis and lysosomal dysfunction, explaining the progressive epilepsy and neuronal cell death in patients with KCTD7 mutations. Ongoing research (2022–2024) has not only clarified these functions with molecular precision but also opened avenues for therapeutic intervention, exemplifying how functional annotation of a previously enigmatic gene can directly inform clinical strategies. The story of KCTD7 – from an obscure “potassium channel tetramerization” protein to a key modulator of calpains and neuronal survival – highlights the power of modern genomics and proteomics in uncovering the critical roles of proteins that were once defined only by name and sequence. (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov)

References: (Key references in chronological order)

• Van Bogaert et al. (2007), Annals of Neurology – Identified KCTD7 mutation in progressive myoclonic epilepsy (pmc.ncbi.nlm.nih.gov).
• Azizieh et al. (2011), Molecular Neurobiology – Demonstrated KCTD7’s hyperpolarizing effect on neurons and interaction with CUL3 (pubmed.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov).
• Staropoli et al. (2012), American Journal of Human Genetics – Linked KCTD7 mutation to ubiquitin-proteasome system and ceroid lipofuscinosis (www.jle.com).
• Liu et al. (2013), Cell & Bioscience – Reviewed KCTD protein family structure/function (pmc.ncbi.nlm.nih.gov).
• Alevy et al. (2019), Neurochemistry International – Kctd7 knockout mouse study showing retinal neurovascular defects (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• Wang et al. (2022), Science Advances – Showed CRL3-KCTD7 targets CLN5 for degradation; explained lysosomal pathology (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• Sharma et al. (2023), Cell Discovery – Identified calpains as substrates of KCTD7-Cullin3 complex; uncovered non-degradative ubiquitination mechanism (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).
• GeneReviews (2025) – Comprehensive clinical synopsis of KCTD7-PME/CLN14, with updated molecular insights (www.ncbi.nlm.nih.gov) (www.ncbi.nlm.nih.gov).

Citations

1. AnnotationURLCitation(end_index=617, start_index=446, title='Progressive myoclonic epilepsy-associated gene KCTD7 is a regulator of potassium conductance in neurons - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/21710140/#:~:text=The%20potassium%20channel%20tetramerization%20domain,in%20the%20hippocampal%20and%20Purkinje')
2. AnnotationURLCitation(end_index=958, start_index=799, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=KCTD7%20has%20been%20shown%20to,ligases%20%28CRLs%29%20and%20function%20as')
3. AnnotationURLCitation(end_index=1165, start_index=1038, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=not%20well%20understood,But%20whether%20and')
4. AnnotationURLCitation(end_index=1435, start_index=1294, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=unknown%20function%20that%20is%20defective,30%20%2C%2032')
5. AnnotationURLCitation(end_index=1756, start_index=1615, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=unknown%20function%20that%20is%20defective,30%20%2C%2032')
6. AnnotationURLCitation(end_index=2128, start_index=1987, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=unknown%20function%20that%20is%20defective,30%20%2C%2032')
7. AnnotationURLCitation(end_index=2788, start_index=2589, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=KCTD7%20is%20expressed%20postnatally%20throughout,causes%20hyperpolarization%20and%20decreased%20excitation')
8. AnnotationURLCitation(end_index=3122, start_index=2947, title='Tissue expression of KCTD7 - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000243335-KCTD7/tissue#:~:text=HUMAN%20PROTEIN%20ATLAS%20INFORMATION,i%7D%20Pending%20normal%20tissue%20annotation')
9. AnnotationURLCitation(end_index=3273, start_index=3123, title='Tissue expression of KCTD7 - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000243335-KCTD7/tissue#:~:text=cluster%20%28RNA%29,i%7D%20Evidence%20at%20protein%20level')
10. AnnotationURLCitation(end_index=3581, start_index=3406, title='Tissue expression of KCTD7 - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000243335-KCTD7/tissue#:~:text=HUMAN%20PROTEIN%20ATLAS%20INFORMATION,i%7D%20Pending%20normal%20tissue%20annotation')
11. AnnotationURLCitation(end_index=3751, start_index=3582, title='Tissue expression of KCTD7 - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000243335-KCTD7/tissue#:~:text=Pending%20normal%20tissue%20annotation,based%20on%20tissue%20RNA%20expression')
12. AnnotationURLCitation(end_index=4074, start_index=3941, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=necessary%20and%20sufficient%20for%20calpain,S1g')
13. AnnotationURLCitation(end_index=4386, start_index=4256, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=KCTD7%20with%20either%20calpain%20subunits,38')
14. AnnotationURLCitation(end_index=4686, start_index=4551, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=match%20at%20L315%20calpain%201,K398R%20expression')
15. AnnotationURLCitation(end_index=4802, start_index=4687, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=calpain%201,K398R%20expression')
16. AnnotationURLCitation(end_index=5319, start_index=5120, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=KCTD7%20is%20expressed%20postnatally%20throughout,causes%20hyperpolarization%20and%20decreased%20excitation')
17. AnnotationURLCitation(end_index=5450, start_index=5320, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=KCTD7%20with%20either%20calpain%20subunits,38')
18. AnnotationURLCitation(end_index=5926, start_index=5767, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=KCTD7%20has%20been%20shown%20to,ligases%20%28CRLs%29%20and%20function%20as')
19. AnnotationURLCitation(end_index=6226, start_index=6072, title='Progressive myoclonic epilepsy-associated gene KCTD7 is a regulator of potassium conductance in neurons - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/21710140/#:~:text=of%20KCTD7%20in%20patients%20with,of%20the%20neuron%20plasma%20membrane%27s')
20. AnnotationURLCitation(end_index=6590, start_index=6463, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=that%20KCTD7%20interacts%20with%20Cullin,3')
21. AnnotationURLCitation(end_index=6799, start_index=6668, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Immunoprecipitation%20%28IP%29%20of%20Cullin,1')
22. AnnotationURLCitation(end_index=7117, start_index=6966, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=1c%20%29.%20Cullin,probably%20functions%20as%20an%20intramolecular')
23. AnnotationURLCitation(end_index=7245, start_index=7118, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Co,an%20adapter%20for%20calpain%20subunits')
24. AnnotationURLCitation(end_index=7521, start_index=7362, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=KCTD7%20has%20been%20shown%20to,ligases%20%28CRLs%29%20and%20function%20as')
25. AnnotationURLCitation(end_index=7803, start_index=7662, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=unknown%20function%20that%20is%20defective,30%20%2C%2032')
26. AnnotationURLCitation(end_index=8396, start_index=8255, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=protein%20of%20previously%20uncharacterized%20function,3')
27. AnnotationURLCitation(end_index=8562, start_index=8397, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=show%20that%20KCTD7%20works%20in,and%20resulted%20in%20calpain%20hyperactivation')
28. AnnotationURLCitation(end_index=8839, start_index=8672, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Calpains%20are%20a%20class%20of,function%20whose%20pathogenic%20mutations%20result')
29. AnnotationURLCitation(end_index=8998, start_index=8840, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Calpains%20are%20a%20unique%20class,to%20the%20involvement%20of%20calpain')
30. AnnotationURLCitation(end_index=9243, start_index=9099, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=interaction%20between%20KCTD7%20and%20calpain,Supplementary')
31. AnnotationURLCitation(end_index=9371, start_index=9244, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Co,an%20adapter%20for%20calpain%20subunits')
32. AnnotationURLCitation(end_index=9629, start_index=9510, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=non,mediated%20ubiquitination%20to')
33. AnnotationURLCitation(end_index=9762, start_index=9630, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=KCTD7%E2%80%93Cullin,2%20at%20K280%20and%20K674')
34. AnnotationURLCitation(end_index=10029, start_index=9910, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=non,mediated%20ubiquitination%20to')
35. AnnotationURLCitation(end_index=10195, start_index=10030, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=show%20that%20KCTD7%20works%20in,and%20resulted%20in%20calpain%20hyperactivation')
36. AnnotationURLCitation(end_index=10503, start_index=10350, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=To%20test%20whether%20calpains%20are,cells%20did%20not%20result%20in')
37. AnnotationURLCitation(end_index=10676, start_index=10504, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=We%20therefore%20sought%20to%20determine,without%20affecting%20their%20protein%20levels')
38. AnnotationURLCitation(end_index=10895, start_index=10723, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=We%20therefore%20sought%20to%20determine,without%20affecting%20their%20protein%20levels')
39. AnnotationURLCitation(end_index=11050, start_index=10896, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=i%29.%20Cleaved%20caspase,ubiquitin%20ligase%20controls%20calpain%201')
40. AnnotationURLCitation(end_index=11472, start_index=11357, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=calpain%201,K398R%20expression')
41. AnnotationURLCitation(end_index=11622, start_index=11473, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=activation.%20Ubiquitination,for%20calpain%201%20stability%20and')
42. AnnotationURLCitation(end_index=11837, start_index=11724, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=calpain%201,CAPNS1%20complex')
43. AnnotationURLCitation(end_index=11987, start_index=11838, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=activation.%20Ubiquitination,for%20calpain%201%20stability%20and')
44. AnnotationURLCitation(end_index=12406, start_index=12278, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=K27,associated%20disease.%20Finally%2C%20we')
45. AnnotationURLCitation(end_index=12561, start_index=12407, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=i%29.%20Cleaved%20caspase,ubiquitin%20ligase%20controls%20calpain%201')
46. AnnotationURLCitation(end_index=12878, start_index=12702, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=calpain%20hyperactivation%2C%20aberrant%20cleavage%20of,shed%20light%20on%20the%20molecular')
47. AnnotationURLCitation(end_index=13215, start_index=13053, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
48. AnnotationURLCitation(end_index=13496, start_index=13334, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
49. AnnotationURLCitation(end_index=13647, start_index=13497, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=a%20unique%20NCL%20subtype,demonstrate%20that%20KCTD7%20and%20CLN5')
50. AnnotationURLCitation(end_index=14022, start_index=13872, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=a%20unique%20NCL%20subtype,demonstrate%20that%20KCTD7%20and%20CLN5')
51. AnnotationURLCitation(end_index=14320, start_index=14170, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=a%20unique%20NCL%20subtype,demonstrate%20that%20KCTD7%20and%20CLN5')
52. AnnotationURLCitation(end_index=14708, start_index=14558, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=a%20unique%20NCL%20subtype,demonstrate%20that%20KCTD7%20and%20CLN5')
53. AnnotationURLCitation(end_index=15045, start_index=14906, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=Lysosomes%20are%20central%20organelles%20for,CLN5%20and')
54. AnnotationURLCitation(end_index=15208, start_index=15046, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
55. AnnotationURLCitation(end_index=15458, start_index=15321, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=enzymes,in%20a%20common%20neurodegenerative%20pathway')
56. AnnotationURLCitation(end_index=15781, start_index=15619, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
57. AnnotationURLCitation(end_index=16168, start_index=16006, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
58. AnnotationURLCitation(end_index=16324, start_index=16169, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=Mechanistically%2C%20the%20CRL3,demonstrate%20that%20KCTD7%20and%20CLN5')
59. AnnotationURLCitation(end_index=17435, start_index=17281, title='Progressive myoclonic epilepsy-associated gene KCTD7 is a regulator of potassium conductance in neurons - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/21710140/#:~:text=of%20KCTD7%20in%20patients%20with,of%20the%20neuron%20plasma%20membrane%27s')
60. AnnotationURLCitation(end_index=17577, start_index=17436, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Bogaert%20et%20al%202007,Azizieh%20et%20al%202011')
61. AnnotationURLCitation(end_index=17887, start_index=17746, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Bogaert%20et%20al%202007,Azizieh%20et%20al%202011')
62. AnnotationURLCitation(end_index=18323, start_index=18124, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=KCTD7%20is%20expressed%20postnatally%20throughout,causes%20hyperpolarization%20and%20decreased%20excitation')
63. AnnotationURLCitation(end_index=18465, start_index=18324, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Bogaert%20et%20al%202007,Azizieh%20et%20al%202011')
64. AnnotationURLCitation(end_index=19039, start_index=18887, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=cause%20human%20disease,calpains%2C%20however%2C%20do%20not%20exist')
65. AnnotationURLCitation(end_index=19624, start_index=19453, title='Progressive myoclonic epilepsy-associated gene KCTD7 is a regulator of potassium conductance in neurons - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/21710140/#:~:text=The%20potassium%20channel%20tetramerization%20domain,in%20the%20hippocampal%20and%20Purkinje')
66. AnnotationURLCitation(end_index=19766, start_index=19625, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Bogaert%20et%20al%202007,Azizieh%20et%20al%202011')
67. AnnotationURLCitation(end_index=20065, start_index=19905, title='JLE - Epileptic Disorders - KCTD7-related progressive myoclonus epilepsy', type='url_citation', url='https://www.jle.com/en/revues/epd/e-docs/kctd7_related_progressive_myoclonus_epilepsy_307897/article.phtml?tab=references#:~:text=,A%20compound')
68. AnnotationURLCitation(end_index=20930, start_index=20829, title='KCTD7 Gene - GeneCards | KCTD7 Protein | KCTD7 Antibody', type='url_citation', url='https://www.genecards.org/cgi-bin/carddisp.pl?gene=KCTD7#:~:text=,KCTD7%20Gene')
69. AnnotationURLCitation(end_index=21301, start_index=21139, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
70. AnnotationURLCitation(end_index=21622, start_index=21460, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
71. AnnotationURLCitation(end_index=21778, start_index=21623, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=Mechanistically%2C%20the%20CRL3,demonstrate%20that%20KCTD7%20and%20CLN5')
72. AnnotationURLCitation(end_index=22304, start_index=22137, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Calpains%20are%20a%20class%20of,function%20whose%20pathogenic%20mutations%20result')
73. AnnotationURLCitation(end_index=22463, start_index=22305, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Calpains%20are%20a%20unique%20class,to%20the%20involvement%20of%20calpain')
74. AnnotationURLCitation(end_index=22918, start_index=22790, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=K27,associated%20disease.%20Finally%2C%20we')
75. AnnotationURLCitation(end_index=23073, start_index=22919, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=i%29.%20Cleaved%20caspase,ubiquitin%20ligase%20controls%20calpain%201')
76. AnnotationURLCitation(end_index=24161, start_index=24010, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=trilaminar%20vascular%20network,of%20the%20superficial%20and%20deep')
77. AnnotationURLCitation(end_index=24316, start_index=24162, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=Together%2C%20these%20data%20suggest%20that,related%20human%20diseases')
78. AnnotationURLCitation(end_index=24643, start_index=24474, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=a%20significant%20increase%20in%20vessel,deep%20layers%20was%20also%20correspondingly')
79. AnnotationURLCitation(end_index=25064, start_index=24904, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=vascular%20layers%20were%20delayed,and%20increased%20vessel%20branching%20in')
80. AnnotationURLCitation(end_index=25219, start_index=25065, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=Together%2C%20these%20data%20suggest%20that,related%20human%20diseases')
81. AnnotationURLCitation(end_index=25511, start_index=25364, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=development%20was%20altered,postnatal%20week%2C%20as%20by%20P12')
82. AnnotationURLCitation(end_index=25840, start_index=25698, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=match%20at%20L408%20conditions%2C%20resulting,s%2Fm%5E%7B2')
83. AnnotationURLCitation(end_index=26421, start_index=26267, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=Together%2C%20these%20data%20suggest%20that,related%20human%20diseases')
84. AnnotationURLCitation(end_index=26549, start_index=26422, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=not%20well%20understood,But%20whether%20and')
85. AnnotationURLCitation(end_index=27126, start_index=26972, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=Together%2C%20these%20data%20suggest%20that,related%20human%20diseases')
86. AnnotationURLCitation(end_index=27246, start_index=27127, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=match%20at%20L58%20Alevy%20et,These')
87. AnnotationURLCitation(end_index=27752, start_index=27624, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=,about%20one%20third%20of%20affected')
88. AnnotationURLCitation(end_index=28282, start_index=28141, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=unknown%20function%20that%20is%20defective,30%20%2C%2032')
89. AnnotationURLCitation(end_index=28663, start_index=28511, title='JLE - Epileptic Disorders - KCTD7-related progressive myoclonus epilepsy', type='url_citation', url='https://www.jle.com/en/revues/epd/e-docs/kctd7_related_progressive_myoclonus_epilepsy_307897/article.phtml?tab=references#:~:text=S,586')
90. AnnotationURLCitation(end_index=28915, start_index=28784, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Immunoprecipitation%20%28IP%29%20of%20Cullin,1')
91. AnnotationURLCitation(end_index=29066, start_index=28916, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=a%20unique%20NCL%20subtype,demonstrate%20that%20KCTD7%20and%20CLN5')
92. AnnotationURLCitation(end_index=29385, start_index=29180, title='JLE - Epileptic Disorders - KCTD7-related progressive myoclonus epilepsy', type='url_citation', url='https://www.jle.com/en/revues/epd/e-docs/kctd7_related_progressive_myoclonus_epilepsy_307897/article.phtml?tab=references#:~:text=opsoclonus,gene%20and%20progressive%20myoclonic%20epilepsy')
93. AnnotationURLCitation(end_index=29538, start_index=29386, title='JLE - Epileptic Disorders - KCTD7-related progressive myoclonus epilepsy', type='url_citation', url='https://www.jle.com/en/revues/epd/e-docs/kctd7_related_progressive_myoclonus_epilepsy_307897/article.phtml?tab=references#:~:text=,1398')
94. AnnotationURLCitation(end_index=29796, start_index=29645, title='JLE - Epileptic Disorders - KCTD7-related progressive myoclonus epilepsy', type='url_citation', url='https://www.jle.com/en/revues/epd/e-docs/kctd7_related_progressive_myoclonus_epilepsy_307897/article.phtml?tab=references#:~:text=,399')
95. AnnotationURLCitation(end_index=30067, start_index=29923, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Molecular%20genetic%20testing%20approaches%20can,see')
96. AnnotationURLCitation(end_index=30309, start_index=30181, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=,about%20one%20third%20of%20affected')
97. AnnotationURLCitation(end_index=30825, start_index=30697, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=K27,associated%20disease.%20Finally%2C%20we')
98. AnnotationURLCitation(end_index=31178, start_index=31024, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=i%29.%20Cleaved%20caspase,ubiquitin%20ligase%20controls%20calpain%201')
99. AnnotationURLCitation(end_index=31492, start_index=31330, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
100. AnnotationURLCitation(end_index=32077, start_index=31945, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=match%20at%20L440%20of%20Purkinje,compared%20to')
101. AnnotationURLCitation(end_index=32218, start_index=32078, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=of%20Purkinje%20cells%20associated%20with,compared%20to')
102. AnnotationURLCitation(end_index=32657, start_index=32481, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=calpain%20hyperactivation%2C%20aberrant%20cleavage%20of,shed%20light%20on%20the%20molecular')
103. AnnotationURLCitation(end_index=32790, start_index=32658, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=death%20associated%20with%20caspase,degradative')
104. AnnotationURLCitation(end_index=33257, start_index=33116, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Kctd7,epoxysuccinyl%20group%20%28active%20moiety%29%20of')
105. AnnotationURLCitation(end_index=33584, start_index=33452, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=death%20associated%20with%20caspase,degradative')
106. AnnotationURLCitation(end_index=34209, start_index=34039, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=pharmacological%20calpain%20inhibitors%20are%20being,23%2C24%2C88%2C89%7D.%20A%20more')
107. AnnotationURLCitation(end_index=34462, start_index=34318, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=match%20at%20L1301%20pharmacodynamics%20of,Google%20Scholar')
108. AnnotationURLCitation(end_index=34833, start_index=34692, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=Kctd7,epoxysuccinyl%20group%20%28active%20moiety%29%20of')
109. AnnotationURLCitation(end_index=34966, start_index=34834, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=death%20associated%20with%20caspase,degradative')
110. AnnotationURLCitation(end_index=35434, start_index=35290, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Molecular%20genetic%20testing%20approaches%20can,see')
111. AnnotationURLCitation(end_index=35746, start_index=35604, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=,allow%20reliable%20recurrence%20risk%20assessment')
112. AnnotationURLCitation(end_index=36281, start_index=36129, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=cause%20human%20disease,calpains%2C%20however%2C%20do%20not%20exist')
113. AnnotationURLCitation(end_index=36782, start_index=36611, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=prevented%20by%20pharmacological%20inhibition%20of,shed%20light%20on%20the%20molecular')
114. AnnotationURLCitation(end_index=37073, start_index=36976, title='8i79 - Cryo-EM structure of KCTD7 in complex with Cullin3 - Summary - Protein Data Bank Japan', type='url_citation', url='https://pdbj.org/mine/summary/8i79#:~:text=8i79%20,3%20%282%20entities%20in%20total')
115. AnnotationURLCitation(end_index=37354, start_index=37257, title='8i79 - Cryo-EM structure of KCTD7 in complex with Cullin3 - Summary - Protein Data Bank Japan', type='url_citation', url='https://pdbj.org/mine/summary/8i79#:~:text=8i79%20,3%20%282%20entities%20in%20total')
116. AnnotationURLCitation(end_index=38444, start_index=38245, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=KCTD7%20is%20expressed%20postnatally%20throughout,causes%20hyperpolarization%20and%20decreased%20excitation')
117. AnnotationURLCitation(end_index=38948, start_index=38811, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=enzymes,in%20a%20common%20neurodegenerative%20pathway')
118. AnnotationURLCitation(end_index=39474, start_index=39298, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=calpain%20hyperactivation%2C%20aberrant%20cleavage%20of,shed%20light%20on%20the%20molecular')
119. AnnotationURLCitation(end_index=39958, start_index=39778, title='JLE - Epileptic Disorders - KCTD7-related progressive myoclonus epilepsy', type='url_citation', url='https://www.jle.com/en/revues/epd/e-docs/kctd7_related_progressive_myoclonus_epilepsy_307897/article.phtml?tab=references#:~:text=Epilepsia.%202012%3B53%3A1387,208')
120. AnnotationURLCitation(end_index=40100, start_index=39959, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Bogaert%20et%20al%202007,Azizieh%20et%20al%202011')
121. AnnotationURLCitation(end_index=40638, start_index=40462, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=calpain%20hyperactivation%2C%20aberrant%20cleavage%20of,shed%20light%20on%20the%20molecular')
122. AnnotationURLCitation(end_index=40771, start_index=40639, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=death%20associated%20with%20caspase,degradative')
123. AnnotationURLCitation(end_index=42077, start_index=41936, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=unknown%20function%20that%20is%20defective,30%20%2C%2032')
124. AnnotationURLCitation(end_index=42249, start_index=42078, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=prevented%20by%20pharmacological%20inhibition%20of,shed%20light%20on%20the%20molecular')
125. AnnotationURLCitation(end_index=42566, start_index=42425, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=unknown%20function%20that%20is%20defective,30%20%2C%2032')
126. AnnotationURLCitation(end_index=42857, start_index=42703, title='Progressive myoclonic epilepsy-associated gene KCTD7 is a regulator of potassium conductance in neurons - PubMed', type='url_citation', url='https://pubmed.ncbi.nlm.nih.gov/21710140/#:~:text=of%20KCTD7%20in%20patients%20with,of%20the%20neuron%20plasma%20membrane%27s')
127. AnnotationURLCitation(end_index=42999, start_index=42858, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=Bogaert%20et%20al%202007,Azizieh%20et%20al%202011')
128. AnnotationURLCitation(end_index=43346, start_index=43148, title='JLE - Epileptic Disorders - KCTD7-related progressive myoclonus epilepsy', type='url_citation', url='https://www.jle.com/en/revues/epd/e-docs/kctd7_related_progressive_myoclonus_epilepsy_307897/article.phtml?tab=references#:~:text=Progressive%20Myoclonus%20Epilepsies%3A%20State,208')
129. AnnotationURLCitation(end_index=43568, start_index=43441, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=not%20well%20understood,But%20whether%20and')
130. AnnotationURLCitation(end_index=43844, start_index=43693, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=trilaminar%20vascular%20network,of%20the%20superficial%20and%20deep')
131. AnnotationURLCitation(end_index=44014, start_index=43845, title='Progressive myoclonic epilepsy-associated gene Kctd7 regulates retinal neurovascular patterning and function - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC6702070/#:~:text=a%20significant%20increase%20in%20vessel,deep%20layers%20was%20also%20correspondingly')
132. AnnotationURLCitation(end_index=44301, start_index=44139, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=accumulation%20of%20ceroid%20in%20neurons,Golgi%20trafficking%20of%20lysosomal')
133. AnnotationURLCitation(end_index=44439, start_index=44302, title='KCTD7 mutations impair the trafficking of lysosomal enzymes through CLN5 accumulation to cause neuronal ceroid lipofuscinoses - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC9348797/#:~:text=enzymes,in%20a%20common%20neurodegenerative%20pathway')
134. AnnotationURLCitation(end_index=44738, start_index=44597, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=protein%20of%20previously%20uncharacterized%20function,3')
135. AnnotationURLCitation(end_index=44893, start_index=44739, title='Calpain activity is negatively regulated by a KCTD7–Cullin-3 complex via non-degradative ubiquitination - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC10038992/#:~:text=i%29.%20Cleaved%20caspase,ubiquitin%20ligase%20controls%20calpain%201')
136. AnnotationURLCitation(end_index=45203, start_index=45004, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=KCTD7%20is%20expressed%20postnatally%20throughout,causes%20hyperpolarization%20and%20decreased%20excitation')
137. AnnotationURLCitation(end_index=45332, start_index=45204, title='KCTD7-Related Progressive Myoclonic Epilepsy - GeneReviews® - NCBI Bookshelf', type='url_citation', url='https://www.ncbi.nlm.nih.gov/books/n/gene/kctd7-epilepsy/#:~:text=,about%20one%20third%20of%20affected')