KIAA1614: An Uncharacterized Human Protein with Predicted Roles in Cell Polarity and Centrosome Function

Introduction and Overview

KIAA1614 (UniProt: Q5VZ46, NCBI Gene ID: 57710) is a human protein-coding gene located on chromosome 1q25.3 that encodes an uncharacterized protein of 1,190 amino acids. Despite being identified more than two decades ago as part of the Kazusa cDNA project, the precise molecular function of KIAA1614 remains experimentally undefined [nagase-2000-kiaa-cloning-abstract]. The protein is annotated as "uncharacterized" in major databases including UniProt and NCBI, reflecting the current state of limited experimental characterization. However, computational analyses and high-throughput studies have provided insights that suggest KIAA1614 may function in cell polarity establishment, centrosome biology, and potentially protein kinase C signaling pathways [ncbi-gene-summary][human-protein-atlas-summary].

The KIAA naming convention derives from the Kazusa DNA Research Institute's systematic effort to clone and sequence unidentified human cDNAs, particularly those encoding large proteins from brain tissue. KIAA1614 was among 100 cDNAs (KIAA1544-KIAA1643) sequenced by Nagase and colleagues in 2000 from human adult and fetal brain cDNA libraries [nagase-2000-kiaa-cloning-abstract]. This origin from brain tissue provides early evidence of neuronal expression, a pattern that has been confirmed by subsequent expression profiling studies.

Gene and Protein Structure

The KIAA1614 gene spans approximately 39 kilobases on chromosome 1q25.3 and contains 9 exons [ncbi-gene-summary]. The gene produces a validated transcript that encodes a 1,190 amino acid protein. The RefSeq database lists two validated protein isoforms: NP_066001.1 (isoform 2) and NP_001414570.1 (isoform 1), suggesting the existence of alternative splicing [ncbi-gene-summary].

Domain analysis reveals that KIAA1614 contains two annotated protein domains. The first is DUF4685 (Domain of Unknown Function 4685; InterPro: IPR032756; Pfam: PF15737), a conserved domain whose biochemical function has not been experimentally determined. Domains of Unknown Function represent a substantial fraction of the Pfam database, comprising over 22% of known protein families as of 2019. While their sequences are evolutionarily conserved across species—indicating biological importance—their specific roles often remain undefined until targeted experimental studies are conducted [uniprot-q5vz46-summary].

The second annotated domain is designated PAR6_homolog (InterPro: IPR051741), which bears sequence similarity to the partitioning defective 6 (PAR6) family of cell polarity proteins. The canonical PAR6 proteins are well-characterized adaptor molecules that contain a PDZ domain and a CRIB-like (Cdc42/Rac interactive binding) motif, enabling them to simultaneously interact with GTP-bound Rac and Cdc42 small GTPases and with atypical protein kinase C (aPKC) isoforms [noda-2001-par6-abstract]. The presence of a PAR6 homolog domain in KIAA1614 suggests potential involvement in cell polarity pathways, though the extent of functional similarity between KIAA1614 and canonical PAR6 proteins requires experimental validation.

Predicted Molecular Function

In the absence of direct experimental characterization, the predicted molecular function of KIAA1614 derives from computational analyses including sequence homology, domain architecture, and coexpression networks. Gene Ontology annotations based on electronic annotation (IEA evidence code) suggest involvement in several biological processes [ncbi-gene-summary][human-protein-atlas-summary]:

The protein is predicted to participate in the centrosome cycle, which encompasses the duplication, maturation, and separation of centrosomes during cell division. This prediction aligns with the presence of the PAR6 homolog domain, as PAR6 proteins localize to centrosomes in mammalian cells. Studies have shown that Par6γ localizes specifically to the mother centriole and controls centrosomal protein composition through a Par6α-dependent pathway, with depletion resulting in defects in ciliogenesis, microtubule organization, and centrosome reorientation during cell migration.

KIAA1614 is also predicted to function in the establishment or maintenance of cell polarity, a fundamental process in epithelial tissues, neurons, and dividing cells. The Par3-Par6-aPKC complex represents a master regulator of cell polarity across metazoans, from C. elegans embryonic asymmetric division to mammalian epithelial apico-basal polarity. The PAR6 homolog domain in KIAA1614 raises the possibility that this protein may participate in polarity-related signaling, potentially through interactions with aPKC or small GTPases.

Additionally, Gene Ontology annotations predict protein kinase C (PKC) binding activity for KIAA1614 [human-protein-atlas-summary]. This is particularly intriguing given that canonical PAR6 proteins bind to atypical PKC isoforms (PKCι/λ and PKCζ) through their N-terminal PB1 domain. If KIAA1614 possesses PKC binding capability, it could function as a scaffold or regulatory protein in PKC-mediated signaling pathways.

Subcellular Localization

Computational predictions and limited experimental data indicate that KIAA1614 localizes to multiple cellular compartments [ncbi-gene-summary][human-protein-atlas-summary]. Gene Ontology annotations predict localization to the apical plasma membrane, cell cortex, and nucleus. These predictions are consistent with the proposed roles in cell polarity, as polarity proteins characteristically localize to specific cortical domains.

The Human Protein Atlas provides experimental immunocytochemistry data suggesting that KIAA1614 localizes to the nuclear membrane and vesicles [human-protein-atlas-summary]. This experimental observation of nuclear membrane localization is noteworthy, as the nuclear envelope represents a specialized membrane system with distinct protein composition. Vesicular localization could indicate involvement in membrane trafficking pathways, which are intimately connected to cell polarity through the targeted delivery of polarity determinants.

The dual nuclear and cytoplasmic distribution observed in most tissues by the Human Protein Atlas suggests that KIAA1614 may shuttle between these compartments or perform distinct functions in different cellular contexts. Nuclear-cytoplasmic shuttling is a common regulatory mechanism for signaling molecules.

Expression Profile and Tissue Distribution

KIAA1614 exhibits ubiquitous expression across human tissues but shows enhanced expression in specific cell types [human-protein-atlas-summary][ncbi-gene-summary]. At the tissue level, the highest RNA expression is observed in the retina (27.3 nTPM), followed by cerebellum (17.7 nTPM), with notable expression also in heart muscle, urinary bladder, and endometrium. The enhanced retinal expression is particularly striking when examined at single-cell resolution.

Single-cell RNA sequencing data from the Human Protein Atlas reveals that rod photoreceptor cells show the highest expression of KIAA1614 among all human cell types, with 139.4 normalized counts per million (nCPM) [human-protein-atlas-summary]. Cone photoreceptor cells (95.2 nCPM) and retinal bipolar cells (77.2 nCPM) also show elevated expression. This pattern of high expression across multiple retinal cell types suggests that KIAA1614 may play a specialized role in the retina, potentially related to the highly polarized structure of photoreceptor cells or the unique functional demands of visual processing.

Within the brain, KIAA1614 shows low regional specificity but has highest expression in the cerebellum (33.2 nTPM). The cerebellum is notable for containing the most abundant neuronal type in the human body—the granule cells—which exhibit highly polarized morphology with distinct axonal and dendritic compartments. Expression clustering analysis suggested involvement in nucleosome-related functions, though this computational prediction requires experimental validation [human-protein-atlas-summary].

At the immune cell level, overexpression has been noted in CD4 T cells, NK cells, and T lymphocytes [ncbi-gene-summary], potentially indicating a role in immune cell biology, though this has not been functionally characterized.

Protein-Protein Interactions

The only experimentally validated protein-protein interaction for KIAA1614 documented in major interaction databases is with neuroglobin (NGB), identified through affinity capture-mass spectrometry [vanacker-2019-neuroglobin-abstract][biogrid-kiaa1614-summary]. This interaction was discovered in a proteomics study by Van Acker and colleagues investigating the neuroglobin interactome in SH-SY5Y neuroblastoma cells under normal and ferroptotic stress conditions.

Neuroglobin is a heme protein expressed predominantly in neurons that provides neuroprotection against various cellular stressors, including conditions that promote ferroptosis—an iron-dependent form of cell death characterized by lipid peroxide accumulation [vanacker-2019-neuroglobin-abstract]. The Van Acker study found that NGB-expressing neuroblastoma cells showed significantly increased resistance to ferroptosis induction. KIAA1614 was identified among the proteins that co-immunoprecipitated with NGB, though the functional significance of this interaction was not specifically characterized in the study.

The biological relevance of the NGB-KIAA1614 interaction remains unclear. Both proteins are expressed in neural tissues, raising the possibility of physiological relevance. However, this interaction was detected in a high-throughput screen and appeared in only one of two experimental replicates, warranting cautious interpretation until confirmed by targeted studies. The observation that NGB interacts with proteins involved in iron metabolism, cell death pathways, and DNA repair suggests that its interactome may be complex and condition-dependent [vanacker-2019-neuroglobin-abstract].

Evolutionary Conservation and Paralogs

KIAA1614 orthologs are found across mammals, with conservation documented in chimpanzee, Rhesus monkey, dog, cow, mouse, and rat [ncbi-gene-summary]. A broader analysis identified orthologs in 177 organisms, indicating substantial evolutionary conservation of this gene across the animal kingdom. Such conservation typically implies functional importance, though it does not necessarily reveal what that function is.

The most significant paralog of KIAA1614 is SYNJ2BP (Synaptojanin 2 Binding Protein), an outer mitochondrial membrane protein with a cytosolic PDZ domain [ncbi-gene-summary]. SYNJ2BP functions as a cellular signaling hub through its PDZ domain, which mediates interactions with multiple partners including synaptojanin 2 (SYNJ2), the cell adhesion molecule TMIGD1, and activin type 2 receptor kinases. SYNJ2BP plays important roles in localizing specific mRNAs to mitochondria and in regulating mitochondrial-ER contact sites.

The paralogous relationship between KIAA1614 and SYNJ2BP suggests possible shared ancestry and potentially related functions. Both proteins may function as adaptor or scaffolding molecules that organize signaling complexes at specific subcellular locations. However, SYNJ2BP is considerably smaller (206 amino acids versus 1,190 amino acids for KIAA1614) and has distinct domain architecture, indicating substantial divergence in their precise molecular functions.

Disease Associations and Clinical Studies

Disease associations for KIAA1614 are currently limited to computational predictions, text-mining approaches, and emerging transcriptomic studies rather than robust genetic evidence. The DISEASES database indicates an association with Fanconi anemia complementation group E based on text mining of biomedical literature, though the confidence level and mechanistic basis for this association are unclear [ncbi-gene-summary].

Cancer Associations

The Human Protein Atlas has identified KIAA1614 as a prognostic marker in several cancers, including glioblastoma multiforme, kidney renal clear cell carcinoma, and rectal adenocarcinoma [human-protein-atlas-summary]. The COSMIC (Catalogue of Somatic Mutations in Cancer) database documents somatic mutations in KIAA1614 across multiple tumor types, though mouse insertional mutagenesis experiments do not support the designation of KIAA1614 as a cancer-causing gene. These prognostic associations likely reflect correlations between KIAA1614 expression levels and patient outcomes rather than causal relationships. Nevertheless, the associations in multiple cancer types suggest that KIAA1614 expression may influence tumor biology, potentially through its predicted roles in cell polarity and centrosome function—both processes frequently dysregulated in cancer.

Supporting this cancer association, a multi-omics integration study of glioma using TCGA data identified KIAA1614 as one of several novel biomarkers "likely helpful in both diagnosis and prognosis" of glioma [bhatnagar-2023-glioma-biomarkers-abstract]. This preprint study used sparse canonical correlation analysis to integrate mRNA, DNA methylation, and miRNA data to discriminate between glioblastoma and lower-grade gliomas. While KIAA1614 was listed among the biomarker candidates alongside genes like PPP1R8, GPBP1L1, and CD300A, no specific mechanistic insight into its role in glioma biology was provided. The identification of KIAA1614 as a glioma biomarker is consistent with its high expression in brain tissue, particularly the cerebellum, and its predicted functions in cell polarity—a process frequently disrupted in cancer.

A case-control study examining KIAA gene variants in breast cancer in a Chinese population analyzed the synonymous SNP rs3795504 in KIAA1614 [pang-2021-kiaa-breast-cancer-abstract]. This variant showed no statistically significant association with breast cancer risk (OR: 1.14, 95% CI: 0.98–1.31, P=0.084), suggesting that common variation in KIAA1614 does not substantially contribute to breast cancer susceptibility in this population.

CRISPR Screen Data

The BioGRID ORCS database documents that KIAA1614 has been identified in 35 hits across 1,396 genome-wide CRISPR screens [biogrid-orcs-summary]. While this indicates the gene has been captured in various functional genomic screens, the specific phenotypes and cell fitness effects across different cell lines require further investigation. The DepMap (Cancer Dependency Map) project, which systematically identifies genes required for cancer cell fitness, has data on KIAA1614 dependency scores, though the gene does not appear to be classified as a core essential gene or a strong cancer dependency based on available summaries.

COVID-19 Gene Expression Signature

A notable finding emerged from COVID-19 transcriptomic research. Zhang and colleagues identified KIAA1614 as one of five critical genes (along with ABCB6, MND1, SMG1, and RIPK3) that form a predictive signature for COVID-19 status in blood samples [zhang-2022-covid-genomic-abstract]. Using max-linear logistic regression analysis of 126 blood samples, this five-gene classifier achieved 100% sensitivity and specificity in distinguishing COVID-19 patients from healthy controls.

KIAA1614 appears in multiple COVID-19 patient subtypes defined by gene expression patterns. Notably, patients in subtype I—characterized by KIAA1614 involvement along with negative SMG1 expression—showed higher ICU admission rates compared to subtype II patients. In the statistical model, KIAA1614 had substantial coefficients (+3.4153 in one competing factor model, -0.4620 in another), and its expression correlated with SMG1 (r = 0.5948). ABCB6 expression positively correlates with KIAA1614 expression, suggesting coordinated regulation of these genes during infection.

The authors suggested that KIAA1614, despite being uncharacterized, "could be fundamental" to understanding COVID-19 pathophysiology and warrants focused investigation for vaccine and therapeutic development [zhang-2022-covid-genomic-abstract]. However, subsequent research analyzing gene expression from nasopharyngeal/oropharyngeal swab samples found that these five critical genes no longer played a decisive role, suggesting that genes functionally associated with SARS-CoV-2 infection may differ from genes associated with COVID-19 disease pathology. The biological mechanism by which KIAA1614 contributes to COVID-19 outcomes remains unknown and represents an intriguing avenue for future investigation.

Genetic Variation Studies

KIAA family genes broadly have been implicated in various complex diseases through genetic association studies. Polymorphisms in KIAA genes have drawn attention in the context of cancers, diabetes, autoimmune diseases, and cardiac disease. However, specific robust GWAS findings implicating KIAA1614 SNPs in disease risk appear limited in the current literature [pang-2021-kiaa-breast-cancer-abstract].

Open Questions

Despite the availability of extensive computational predictions, several fundamental questions about KIAA1614 remain unanswered and represent priorities for future investigation:

What is the primary molecular function of KIAA1614? The protein is annotated as "uncharacterized" because no biochemical activity has been experimentally demonstrated. Is it an enzyme, a scaffolding protein, a regulatory adaptor, or something else entirely? The predicted PKC binding activity requires experimental validation.

What is the functional significance of the PAR6 homolog domain? Does KIAA1614 participate in the same cell polarity pathways as canonical PAR6 proteins? Does it interact with atypical PKC, Cdc42/Rac GTPases, or other known polarity components? The extent of functional overlap with PAR6 family members needs to be determined.

Why is KIAA1614 highly expressed in photoreceptor cells? The striking enrichment in rod and cone photoreceptors suggests a specialized function in these highly polarized cells. Does KIAA1614 contribute to photoreceptor development, maintenance, or function? Are there retinal phenotypes in knockout animal models?

What is the biological significance of the neuroglobin interaction? The Van Acker study identified KIAA1614 as a potential NGB interactor, but the functional relevance of this interaction remains unexplored. Does KIAA1614 modulate NGB's neuroprotective function or participate in ferroptosis regulation?

What is the function of the DUF4685 domain? This domain is present in KIAA1614 and presumably in other proteins, yet its biochemical function is unknown. Structural biology and comparative genomics approaches may help elucidate its role.

Does KIAA1614 localize to centrosomes? The predicted involvement in centrosome biology should be testable through localization studies in cycling cells. If confirmed, what role does it play—structural, regulatory, or both?

What is the mechanistic basis for KIAA1614's association with COVID-19 severity? The identification of KIAA1614 as one of five critical genes in a COVID-19 transcriptomic signature raises intriguing questions about its potential role in immune responses or viral pathogenesis. Does KIAA1614 expression change during viral infection, and if so, through what mechanism? Is this association with COVID-19 severity direct or does it reflect broader dysregulation of cell polarity or other pathways during severe disease?

What are the phenotypes of KIAA1614 knockout in model organisms? While the gene is conserved across vertebrates, no phenotype data from targeted knockouts appears to be publicly available. Generation and phenotyping of KIAA1614 knockout mice through resources like IMPC would provide critical insights into the gene's physiological functions.

Addressing these questions will require targeted experimental approaches including protein interaction studies (co-immunoprecipitation, proximity labeling), localization studies (live cell imaging, immunofluorescence), functional studies (knockout/knockdown phenotypes in cell culture and animal models), and structural characterization. The high expression in retina makes this tissue and photoreceptor cell culture models particularly attractive systems for investigating KIAA1614 function. The unexpected connection to COVID-19 severity also suggests that immune cell models may be informative for understanding KIAA1614 biology.

References

1. [nagase-2000-kiaa-cloning-abstract] Nagase T, Kikuno R, Nakayama M, Hirosawa M, Ohara O. Prediction of the coding sequences of unidentified human genes. XVIII. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro. DNA Res. 2000 Aug 31;7(4):273-81. PMID: 10997877. DOI: 10.1093/dnares/7.4.271. https://pubmed.ncbi.nlm.nih.gov/10997877/

2. [vanacker-2019-neuroglobin-abstract] Van Acker ZP, Van Raemdonck GA, Logie E, Van Acker SI, Baggerman G, Vanden Berghe W, Ponsaerts P, Dewilde S. Connecting the Dots in the Neuroglobin-Protein Interaction Network of an Unstressed and Ferroptotic Cell Death Neuroblastoma Model. Cells. 2019 Aug 11;8(8):873. PMID: 31405213. PMCID: PMC6721670. DOI: 10.3390/cells8080873. https://pubmed.ncbi.nlm.nih.gov/31405213/

3. [khambata-ford-2003-promoters-abstract] Khambata-Ford S, Liu Y, Gleason C, Dickson M, Altman RB, Batzoglou S, Myers RM. Identification of promoter regions in the human genome by using a retroviral plasmid library-based functional reporter gene assay. Genome Res. 2003 Jul;13(7):1765-74. PMID: 12805274. PMCID: PMC403750. DOI: 10.1101/gr.529803. https://pubmed.ncbi.nlm.nih.gov/12805274/

4. [noda-2001-par6-abstract] Noda Y, Takeya R, Ohno S, Naito S, Ito T, Sumimoto H. Human homologues of the Caenorhabditis elegans cell polarity protein PAR6 as an adaptor that links the small GTPases Rac and Cdc42 to atypical protein kinase C. Genes Cells. 2001 Feb;6(2):107-19. PMID: 11260256. DOI: 10.1046/j.1365-2443.2001.00404.x. https://pubmed.ncbi.nlm.nih.gov/11260256/

5. [ncbi-gene-summary] NCBI Gene Database. KIAA1614 KIAA1614 [Homo sapiens (human)]. Gene ID: 57710. https://www.ncbi.nlm.nih.gov/gene/57710

6. [human-protein-atlas-summary] Human Protein Atlas. KIAA1614 protein expression summary. Ensembl: ENSG00000135835. https://www.proteinatlas.org/ENSG00000135835-KIAA1614

7. [biogrid-kiaa1614-summary] BioGRID Database. NGB - KIAA1614 Interaction Summary. Interaction ID: 2756644. https://thebiogrid.org/interaction/2756644

8. [uniprot-q5vz46-summary] UniProt Consortium. UniProtKB entry Q5VZ46 - Uncharacterized protein KIAA1614 - Homo sapiens (Human). https://www.uniprot.org/uniprotkb/Q5VZ46

9. [zhang-2022-covid-genomic-abstract] Zhang Z, Guo L, Huang L, Deng Q, et al. The Existence of At Least Three Genomic Signature Patterns and At Least Seven Subtypes of COVID-19 and the End of the Disease. J Data Sci. 2022 Apr;20(2):145-167. PMID: 35529157. PMCID: PMC9146581. DOI: 10.6339/22-JDS1040. https://pmc.ncbi.nlm.nih.gov/articles/PMC9146581/

10. [pang-2021-kiaa-breast-cancer-abstract] Pang H, Zhao Y, Qin Z, Xu X, Ren Q, Song T, Li J, Zhu F, Liu D, Zhong Y. Potential functional variants of KIAA genes are associated with breast cancer risk in a case control study. Ann Transl Med. 2021 May;9(9):764. PMID: 34012873. PMCID: PMC8105804. DOI: 10.21037/atm-20-8028. https://pmc.ncbi.nlm.nih.gov/articles/PMC8105804/

11. [bhatnagar-2023-glioma-biomarkers-abstract] Bhatnagar R, et al. Integration of Multi-omics Data for the Classification of Glioma Types and Identification of Novel Biomarkers. bioRxiv. 2023 Dec 22. DOI: 10.1101/2023.12.22.572983. https://www.biorxiv.org/content/10.1101/2023.12.22.572983v1 (Preprint)

12. [biogrid-orcs-summary] BioGRID ORCS Database. KIAA1614 CRISPR Screens (Homo sapiens). Gene ID: 57710. https://orcs.thebiogrid.org/Gene/57710

Citations

1. bhatnagar-2023-glioma-biomarkers-abstract.md
2. biogrid-kiaa1614-summary.md
3. biogrid-orcs-summary.md
4. human-protein-atlas-summary.md
5. khambata-ford-2003-promoters-abstract.md
6. nagase-2000-kiaa-cloning-abstract.md
7. ncbi-gene-summary.md
8. noda-2001-par6-abstract.md
9. pang-2021-kiaa-breast-cancer-abstract.md
10. uniprot-q5vz46-summary.md
11. vanacker-2019-neuroglobin-abstract.md
12. zhang-2022-covid-genomic-abstract.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 and approach
- Verified identity: KIAA1614 is a human protein encoded by the KIAA1614 gene; UniProt accession Q5VZ46; organism Homo sapiens.
- Because primary literature directly characterizing KIAA1614 is extremely limited and our literature-gathering step did not return citable evidence, this report emphasizes: (i) identity verification, (ii) conservative functional inferences from annotated domains (DUF4685/IPR032756; PAR6_homolog/IPR051741; PF15737), and (iii) clear separation of inference versus experimentally demonstrated biology. Where evidence is lacking, we state uncertainty. If you need deeper validation, targeted experiments are recommended.

Key concepts and definitions (current understanding)
- Gene/protein identity: KIAA1614 (UniProt Q5VZ46) encodes an uncharacterized human protein originally identified via large-scale cDNA sequencing. The protein currently lacks an experimentally validated molecular function and pathway assignment.
- Domain architecture (bioinformatic annotations):
- DUF4685 (PF15737; InterPro IPR032756) is a Domain of Unknown Function; by definition, it has no established, conserved biochemical activity. Presence of DUF4685 supports that KIAA1614 is poorly characterized and likely non-enzymatic or of unknown enzymatic/adaptor role. This is an inference based on the DUF designation rather than direct experimentation.
- PAR6_homolog (InterPro IPR051741) annotation suggests remote homology to Par6-like modules used in polarity scaffolding complexes (Par3–Par6–aPKC) in metazoans. Such annotations can arise from weak sequence/profile similarity and do not guarantee function. If genuine, it would suggest a scaffold/adaptor role in cell polarity signaling; however, without experimental corroboration in KIAA1614, this remains speculative.

Recent developments and latest research (2023–2024)
- No directly citable 2023–2024 primary studies conclusively define KIAA1614 protein function, localization, or interaction partners. Signals in recent high-throughput genetics or transcriptomics sometimes refer to KIAA1614 or to KIAA1614-AS1 (an antisense lncRNA at the locus). Any locus-level statistical associations should be interpreted cautiously until colocalization and gene-level perturbation confirm attribution to the protein-coding gene versus nearby transcripts. Because the evidence could not be retrieved here for citation, we refrain from specific claims.

Current applications and real-world implementations
- There are currently no validated clinical applications (diagnostic, prognostic, or therapeutic) specifically leveraging the KIAA1614 protein. Any potential use discussed in secondary analyses would require replication and mechanistic studies distinguishing effects of the protein-coding gene from non-coding transcripts in the locus.

Expert opinions and analysis from authoritative sources
- Curated protein databases (e.g., UniProt/InterPro) list KIAA1614 as an uncharacterized protein, consistent with the lack of peer-reviewed, experimentally validated function. Domain-level inferences (DUF4685; PAR6-like) suggest a likely non-enzymatic role (e.g., scaffolding/adaptor) but remain unproven. Until orthogonal evidence (biochemistry, structural biology, CRISPR perturbations with rescue) is published, KIAA1614 should be considered function-unknown.

Relevant statistics and data from recent studies
- Not available for confident reporting without access to citable datasets. Some large-scale resources (e.g., GTEx, Human Protein Atlas) may report baseline expression, but specific expression patterns and subcellular localization for KIAA1614 vary by annotation version and require careful validation. Because we could not retrieve citable evidence in this session, we avoid quantitative claims.

Functional inference and testable hypotheses
- If the PAR6_homolog annotation reflects genuine homology, KIAA1614 may participate in cell polarity/signaling scaffolds. Testable predictions: (i) interaction with Par proteins or aPKC components; (ii) localization to polarity-associated compartments (apical junctions) in epithelial cells. Experimental strategies: affinity purification–mass spectrometry (AP–MS) in polarized epithelial lines; co-immunoprecipitation with Par6/Par3/aPKC; loss-of-function via CRISPR and phenotyping of polarity and junctional integrity; rescue with domain-deletion constructs to test DUF4685/PAR6-like motif contribution.
- If DUF4685 is a conserved fold with peptide-binding capacity (unknown), KIAA1614 could function as an adaptor. Strategies: yeast two-hybrid and peptide-array screens; structural prediction (AlphaFold2) to identify conserved surfaces and mutagenesis of predicted binding patches.

Subcellular localization
- Unresolved. Without validated antibodies and microscopy or tagged endogenous expression data, subcellular distribution is uncertain. If a polarity-related role exists, membrane-proximal/cortical or junctional localization would be plausible, but this is hypothetical.

Pathways and interactions
- Unresolved. No validated pathway membership can be assigned at this time. Any associations from statistical genetics require functional follow-up.

Disease and trait associations
- Unresolved at the level of mechanistic causality. Signals near the KIAA1614 locus may implicate the region in some datasets, but distinguishing effects attributable to KIAA1614 versus the antisense lncRNA KIAA1614-AS1 or neighboring genes is essential. Robust assignment requires: (i) fine-mapping and colocalization with eQTLs that specifically alter KIAA1614 mRNA; (ii) directionally consistent MR across independent cohorts; and (iii) cellular perturbation evidence linking altered KIAA1614 levels to disease-relevant phenotypes.

Data resources and URLs (for follow-up verification by the reader)
- UniProt entry for KIAA1614 (Q5VZ46): https://www.uniprot.org/uniprot/Q5VZ46
- InterPro entries: DUF4685 (IPR032756); PAR6_homolog (IPR051741): https://www.ebi.ac.uk/interpro/
- Pfam DUF4685 (PF15737): http://pfam.xfam.org/family/PF15737
- Ensembl gene (ENSG00000135835) and locus transcripts (including antisense lncRNA): https://www.ensembl.org
- GTEx (baseline expression/eQTLs; verify attribution to the protein-coding gene versus antisense lncRNA): https://gtexportal.org/
- Human Protein Atlas (expression/localization; validate antibody reliability): https://www.proteinatlas.org/

Conclusion
- Mandated verification satisfied: KIAA1614 (UniProt Q5VZ46) is the correct human, uncharacterized protein with DUF4685 and a tentative PAR6_homolog domain annotation. The current peer-reviewed literature does not provide definitive molecular function, localization, or pathway assignment for the protein. Any locus-level genetic associations should not be over-interpreted without gene-level functional validation and careful separation from KIAA1614-AS1 signals. The most appropriate next steps are experimental characterization focusing on interaction partners, localization in polarized cells, and perturbation phenotyping to assess roles in polarity or scaffolding. Because we were unable to retrieve citable primary evidence in this session, the above remains a conservative synthesis anchored to database identity and principled inference from domain annotations.

Citations

1. https://www.uniprot.org/uniprot/Q5VZ46
2. https://www.ebi.ac.uk/interpro/
3. http://pfam.xfam.org/family/PF15737
4. https://www.ensembl.org
5. https://gtexportal.org/
6. https://www.proteinatlas.org/

Introduction and Gene Identification

KIAA1614 is a human gene originally identified through large-scale cDNA projects as encoding a protein of unknown function (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The gene (located on chromosome 1q25.3) codes for a sizable protein (approximately 1,190 amino acids for the longest isoform) with no well-characterized homologs or enzymatic domains. It is often referred to by its cDNA designation “KIAA1614” due to the lack of a descriptive name, underscoring that its function remains uncharacterized. Critically, KIAA1614 should not be confused with other similarly named genes – it is unique to Homo sapiens (with orthologs in mammals) and the symbol KIAA1614 does not denote any unrelated protein (www.proteinatlas.org) (www.proteinatlas.org). Current data confirm that the KIAA1614 mRNA is expressed and translated in human tissues (evidence at transcript and protein level) (www.proteinatlas.org). Below, we compile the key information on KIAA1614’s predicted structure, function, localization, and emerging links to biological processes, drawing on recent databases and studies.

Protein Structure and Domains

KIAA1614 is classified as a predicted intracellular protein without any transmembrane regions or signal peptide (www.proteinatlas.org) (www.proteinatlas.org). Its sequence contains a notable region of homology to Partitioning-defective 6 (Par6), a scaffold protein known for its role in cell polarity. In particular, KIAA1614 harbors a PB1 domain-like module (identified by InterPro as a “PAR6_homolog” region) (www.proteinatlas.org). PB1 domains mediate heterodimerization in signaling complexes; for example, Par6 uses its PB1 domain to bind atypical Protein Kinase C (aPKC) as part of the Par3-Par6-aPKC polarity complex (www.ncbi.nlm.nih.gov). By analogy, the presence of a Par6-type PB1 domain suggests KIAA1614 might similarly interact with PKC isoforms. In fact, computational gene ontology annotations predict KIAA1614 has protein kinase C binding activity (www.proteinatlas.org), hinting that it could serve as an adaptor that recruits PKC or related proteins into larger complexes.

Apart from the PB1-like region, KIAA1614 contains a Domain of Unknown Function 4685 (DUF4685), as catalogued in Pfam (PF15737) and CDD (www.ncbi.nlm.nih.gov). This DUF4685 is a ~110–130 amino acid module with two conserved motifs (“SGE” and “VRF”) but no ascribed biochemical function (www.ncbi.nlm.nih.gov). Notably, DUF4685 is found in vertebrate proteins (www.ncbi.nlm.nih.gov), suggesting it could confer a regulatory or structural role unique to this family. No enzymatic active sites or known catalytic motifs are present in KIAA1614, aligning with the idea that it functions as a scaffold or regulatory protein rather than an enzyme (www.proteinatlas.org). Consistent with this, the protein lacks signal sequences and is not secreted; it resides inside cells where it may organize other proteins. KIAA1614’s primary sequence length varies due to alternative splicing – at least two isoforms exist (811 amino acids and 1190 amino acids) (www.proteinatlas.org). These isoforms share the core domains, but the longer form includes additional regions (potentially including the full DUF4685) that might influence its interactions or localization. To date, however, no study has definitively mapped functional motifs in KIAA1614 through mutational analysis, so our structural understanding relies on bioinformatic predictions.

Expression and Subcellular Localization

Available gene expression profiles indicate that KIAA1614 is widely expressed at low-to-moderate levels in human tissues. RNA sequencing data show ubiquitous transcription: for instance, NCBI’s expression summary reports KIAA1614 expression (RPKM ~1–2) in thyroid, ovary, and at least 22 other tissues (www.ncbi.nlm.nih.gov). The Human Protein Atlas further classifies KIAA1614 as “detected in many” tissues, with enhanced expression in the retina (www.proteinatlas.org). This retina enrichment suggests a possible specialized role in retinal cells, which are highly polarized and structurally specialized. Indeed, many KIAA proteins identified from brain cDNA libraries (like KIAA1614) tend to have important roles in the nervous system (pmc.ncbi.nlm.nih.gov), and retina is an extension of the central nervous system.

At the cellular level, KIAA1614’s location appears to be both cytoplasmic and nuclear. Immunohistochemical data (using an anti-KIAA1614 antibody) show a combination of cytoplasmic and nuclear staining in most analyzed cell types (www.proteinatlas.org). This dual localization is in line with the computational prediction that the protein can operate at the cell periphery and inside the nucleus. Notably, Gene Ontology annotations predict KIAA1614 to localize to the apical plasma membrane and cell cortex, as well as the nucleus (www.proteinatlas.org). The apical membrane/cortex localization would be consistent with a role in polarized cells – for example, it might situate at the apical side of epithelial cells (where Par6/aPKC polarity complexes act) or at centrosomes. Its predicted presence at the cell cortex aligns with involvement in cell junctions or the cytoskeletal architecture that defines cell shape (www.proteinatlas.org). Concurrently, a nuclear presence hints at a regulatory function that could involve shuttling between the cytoplasm and nucleus, perhaps affecting gene expression or chromatin organization indirectly. It is possible that different isoforms or different cell-cycle stages dictate KIAA1614’s localization: for instance, one splice variant might remain in the cytoplasm to scaffold signaling complexes, while another variant or condition (e.g. cell stress) sends it to the nucleus. However, experimental validation is lacking – the immunolocalization data are preliminary (the protein atlas notes some antibody reliability issues) (www.proteinatlas.org). Thus, while the prevailing model is that KIAA1614 is an intracellular protein with both membrane-adjacent (cortical) and nuclear roles, higher-resolution studies (such as tagged protein imaging) are needed to confirm this distribution.

Predicted Functions and Biological Processes

Despite the absence of direct functional studies, multiple lines of evidence converge on the idea that KIAA1614 is involved in cellular polarity and organization. The Alliance of Genome Resources functional summary (updated 2022–2025) assigns KIAA1614 a role in “establishment or maintenance of cell polarity” (www.proteinatlas.org). Cell polarity refers to the asymmetric organization of cellular components – a fundamental feature in epithelial cells, neurons, and other specialized cells. Proteins that regulate polarity often control the positioning of organelles, the direction of vesicle traffic, or the formation of junctions between cells. KIAA1614’s similarity to Par6 and predicted ability to bind aPKC suggest it could be part of a polarity complex that dictates which side of the cell is “apical” versus “basal” (www.proteinatlas.org). Notably, Par6/aPKC complexes also interact with small GTPases (like Cdc42) to translate extracellular cues into polarized cell growth; if KIAA1614 joins this complex, it might act as an additional scaffold or regulator to fine-tune these signals.

Another predicted biological process for KIAA1614 is the centrosome cycle (www.proteinatlas.org). The centrosome cycle involves duplication and segregation of centrosomes, which organize the microtubule spindle during mitosis. Proteins involved here often ensure that the centrosomes duplicate only once per cell cycle and position correctly for cell division. KIAA1614’s association with the centrosome cycle (in GO annotations) could mean it localizes to centrosomes or interacts with centrosomal components to influence their function. For example, some polarity proteins also localize to centrosomes/mitotic spindles in dividing cells to ensure symmetric vs. asymmetric cell divisions. It is conceivable that KIAA1614, through its scaffolding role, helps anchor signaling molecules (like PKC or other kinases) at the centrosome or mitotic spindle to coordinate cell division with polarity cues.

Moreover, KIAA1614 is predicted to be involved in “regulation of cellular localization” of other molecules (www.proteinatlas.org). This broad phrase in GO terms suggests a role in transporting or sequestering proteins within specific cellular compartments. Given its potential binding to PKC and perhaps other proteins, KIAA1614 might regulate where in the cell certain signaling enzymes or structural proteins reside. For instance, it might retain aPKC at the cell cortex until signals trigger its release to the nucleus (or vice versa). Such “location control” is a common theme in cell signaling – scaffold proteins like AKAPs, PDZ-domain proteins, or Par6 itself often determine the locality of signaling events. KIAA1614 could be a novel member of this class, ensuring that particular proteins are at the right place (e.g., apical membrane, centrosome, or nucleus) at the right time.

Importantly, all these functions remain putative. To date, no direct biochemical assay (such as an enzymatic activity test or ligand-binding experiment) has been reported for KIAA1614. The functional assertions are derived from high-throughput data integration and computational inference (www.proteinatlas.org). For example, the protein kinase C-binding prediction comes from the presence of a PB1 domain and known interaction motifs; experimental confirmation (e.g., co-immunoprecipitation with PKC) has not been published. Similarly, the association with cell polarity and centrosomes comes from guilt-by-association (homology to polarity proteins, or perhaps co-expression with known polarity regulators). Thus, while the current understanding posits KIAA1614 as a non-enzymatic regulator that links signaling molecules to cell structural elements, this model awaits validation. We can anticipate that knockout or knockdown studies (for instance, using CRISPR or RNAi) would clarify if loss of KIAA1614 disrupts cell polarity, cell division, or protein localization in cells. Likewise, proteomic interaction mapping could identify binding partners and place KIAA1614 in a definitive pathway.

Interaction Networks and Pathway Involvement

Protein–protein interaction data for KIAA1614 are limited but suggestive. Large-scale interaction databases (e.g. BioGRID) list a small number of interacting partners for KIAA1614, though these are derived from high-throughput experiments and not yet individually confirmed (thebiogrid.org). In one proteomic study examining neuroblastoma cells, KIAA1614 was identified among a network of proteins interacting with neuroglobin in the context of oxidative stress and ferroptosis (www.ncbi.nlm.nih.gov). While the full details were not elaborated in the publication, the finding implies that KIAA1614 might associate (directly or indirectly) with stress-response proteins in neuronal cells. This could tie into its predicted role in cellular organization – for example, neuroglobin interactions might occur at the cell cortex or in specific subcellular domains where KIAA1614 is present.

Another hint of KIAA1614’s network comes from predictive interaction tools. The STRING database, which integrates known and predicted associations, suggests that KIAA1614 might functionally link with proteins involved in RNA processing and cell junctions (for instance, it lists partners like FIP1L1 and CPSF3, components of mRNA polyadenylation machinery, as high-score predictions) (string-db.org). These predicted links are intriguing: if valid, they raise the possibility that KIAA1614 connects cell polarity with gene expression – perhaps by anchoring RNA-processing enzymes in specific cell regions or stress conditions. However, such predictions rely on indirect evidence (co-expression or text mining) and should be interpreted cautiously until validated. It is also possible that these interactions are cell-type specific; e.g., in certain developmental contexts KIAA1614 might bind an mRNA regulator, whereas in polarized epithelial cells it binds aPKC.

The most compelling potential interaction remains with atypical PKC isoforms (such as PKCζ or PKCι/λ), due to the PB1 domain. Par6 family proteins dimerize with aPKC via PB1-PB1 domain interaction (www.ncbi.nlm.nih.gov), and notably, Par6 itself also binds the small GTPase Cdc42 (through a CRIB domain) to regulate aPKC activity at the cell cortex. KIAA1614 lacks the CRIB motif of Par6 (so it may not bind Cdc42 directly), but if it binds aPKC, it could compete with or complement Par6 in polarity complexes. For example, KIAA1614 might form an alternate complex with aPKC at the centrosome or nucleus, whereas Par6/aPKC operates at tight junctions. No experimental interaction map of KIAA1614 has been published to confirm this, but the protein kinase C binding prediction is a key hypothesis driving current thinking about KIAA1614’s pathway involvement (www.proteinatlas.org).

Given the dearth of focused studies on KIAA1614, it is not yet assigned to any canonical signaling pathway (e.g., it’s not in KEGG or Reactome charts). Instead, its pathway involvement is being deduced from the contexts where its gene expression or epigenetic status changes (discussed below). These contexts – which include cell adhesion, inflammation, and cell stress – all hint that KIAA1614 might interface with pathways that govern the cytoskeleton and cell-environment interactions. For instance, the recurring theme of “adhesion molecules” in genetic studies (next section) suggests KIAA1614 could be linked to pathways like integrin signaling or epithelial junction formation. If KIAA1614 indeed localizes to the apical membrane and cell cortex, it might interact with components of adherens junctions or tight junctions, helping cells maintain contact and polarity. This places KIAA1614 at a nexus of signaling and structural networks – potentially acting as a bridge between kinase signaling (PKC, etc.) and the cytoskeletal or junctional apparatus.

Disease Associations and Current Applications

Although KIAA1614’s molecular function is still being unraveled, recent research has implicated KIAA1614 in several disease-related contexts, primarily through genomic and epigenomic studies. These associations provide clues to its possible biological roles and hint at future applications (e.g. as a biomarker):

• Inflammatory Bowel Disease (IBD) and Gut Epithelium: In ulcerative colitis – a form of IBD characterized by chronic colon inflammation – KIAA1614 was identified as part of a hypermethylated gene panel. A 2016 genome-wide DNA methylation analysis found that the KIAA1614 promoter is significantly hypermethylated in colitis patients, correlating with transcriptional silencing of the gene (maayanlab.cloud). Since DNA hypermethylation often indicates down-regulation of gene expression, this suggests that KIAA1614 expression is lost in inflamed colon tissue. The authors proposed that such epigenetic inactivation may contribute to disease pathogenesis (maayanlab.cloud). One interpretation is that KIAA1614 might normally help maintain the integrity or polarity of colonic epithelial cells, and when its expression is silenced, the epithelial barrier or organization could be compromised, exacerbating inflammation. While causal links remain to be proven, KIAA1614 could emerge as part of an epigenetic biomarker panel for ulcerative colitis or a mechanistic link between chronic inflammation and loss of epithelial polarity.

• Metabolic Regulation (Metformin Response): An intriguing 2018 study on the epigenetic effects of the anti-diabetic drug metformin found that KIAA1614 is a target of metformin-induced methylation changes (maayanlab.cloud). In healthy individuals given short-term metformin, the DNA methylation at the KIAA1614 locus was altered (relative to baseline), suggesting the gene’s regulation is responsive to metabolic state or AMPK pathway activation (metformin’s primary action). This finding implies that KIAA1614 might be involved in metabolic signaling networks or stress responses. If metformin’s effects on KIAA1614 influence cell polarity or adhesion, it could be relevant to how metabolic drugs affect cell architecture or even cancer (metformin is studied for anti-cancer properties). Practically, this result highlights KIAA1614 as a gene of interest in pharmaco-epigenomics; its methylation status could potentially serve as a readout of a patient’s response to metformin or metabolic health, though more data are needed.

• Pregnancy and Development (Implantation): Another epigenetic study, in the context of ectopic pregnancy, found KIAA1614 to be noteworthy. In 2021, researchers profiling chorionic tissue (placental tissue) in ectopic versus normal pregnancies discovered aberrant methylation of KIAA1614 in ectopic pregnancy samples (maayanlab.cloud). Network analysis placed KIAA1614 among a group of genes involved in the regulation of cell adhesion in trophoblastic/chorionic cells (maayanlab.cloud). An ectopic pregnancy involves the embryo implanting outside the uterus, often due to improper adhesion and signaling in the fallopian tube tissue. The implication is that KIAA1614 might contribute to proper embryo implantation, possibly through its role in cell adhesion signaling at the maternal-fetal interface. Abnormal silencing or expression of KIAA1614 could disturb how embryonic cells attach or invade, leading to implantation failures. While this is a very specific context, it underscores KIAA1614’s link to adhesion processes and suggests a potential role in reproductive medicine research. In the future, methylation status of KIAA1614 (in, say, endometrial biopsies) might be explored as a marker for implantation issues or ectopic pregnancy risk, if this association is confirmed.

• Crohn’s Disease Progression: Beyond ulcerative colitis, Crohn’s disease (another IBD) has also been connected to KIAA1614 via genetics. A 2018 report on Crohn’s disease outcomes noted a single-nucleotide variant near the KIAA1614 gene associated with faster progression from uncomplicated disease to complicated disease (such as strictures or fistulas) (maayanlab.cloud). Although this was a “suggestive” association (not yet genome-wide significant), it aligns with the theme that KIAA1614 or its genomic neighborhood might influence inflammatory processes. It’s plausible that genetic differences affecting KIAA1614 expression or function could impact how the intestinal epithelium responds to chronic inflammation, thereby affecting disease severity. For clinicians and researchers, such data hint that KIAA1614 could be part of the genetic risk architecture for IBD complications – a potential prognostic genetic marker if validated in larger cohorts.

• Cardiovascular Disease and Adhesion Molecules: KIAA1614 has also surfaced in the context of cardiovascular risk factors. In the Multi-Ethnic Study of Atherosclerosis, a 2016 multi-protein QTL analysis examined how genetic loci influence levels of circulating cellular adhesion molecules (CAMs) – proteins like ICAM1, VCAM1 that mediate leukocyte adhesion in blood vessels. A significant association was observed at a locus near KIAA1614 with levels of certain adhesion proteins (maayanlab.cloud). This suggests KIAA1614 may be linked to the regulation of adhesion molecule expression or release. While the association was attributed to a locus (and the causal gene could be KIAA1614 or a neighbor), the authors specifically noted KIAA1614 in discussing regulatory candidates for adhesion processes (maayanlab.cloud). If KIAA1614 indeed modulates CAM levels, it could tie into atherosclerosis by affecting endothelial cell interaction with immune cells – again pointing to a role in cell-cell adhesion contexts. From an application standpoint, this insight connects KIAA1614 to a possible impact on cardiovascular inflammation; it might become a target for further study in vascular biology or even a biomarker linking genetic makeup to inflammation levels.

• Cancer Biomarker Potential: Direct studies of KIAA1614 in cancer biology are lacking, but data from the Human Protein Atlas (HPA) hint that KIAA1614 expression correlates with patient outcomes in certain cancers. According to HPA analysis, KIAA1614 mRNA is expressed across many cancer types with low specificity (not restricted to one cancer) (www.proteinatlas.org), and its protein is detectable in common cancers (e.g., colorectal, breast, prostate) (www.proteinatlas.org). Notably, Kaplan-Meier analyses in HPA found KIAA1614 to be a prognostic marker in at least three cancers: in colorectal cancer, higher KIAA1614 expression is associated with a favorable prognosis (p < 0.001) (www.proteinatlas.org); in kidney renal clear cell carcinoma, higher expression is also linked to better survival (validated, p < 0.001) (www.proteinatlas.org); but in glioblastoma (a type of brain tumor), higher KIAA1614 correlates with worse survival (p < 0.001) (www.proteinatlas.org). These patterns suggest that KIAA1614’s role might differ by context – in highly proliferative, polarity-disrupted tumors like colorectal cancer, retaining KIAA1614 expression may help maintain some epithelial characteristics (thus slowing metastasis, leading to better outcomes) (www.proteinatlas.org). In contrast, in glioblastoma (an aggressive cancer where cell polarity programs are often hijacked), KIAA1614 expression might be associated with tumor-promoting processes (perhaps aiding tumor cell invasion or interaction with the microenvironment) (www.proteinatlas.org). It must be stressed that these are correlative findings and KIAA1614 is not yet a clinical biomarker. However, such data justify further research: e.g., does knocking down KIAA1614 in colon cancer cells make them more invasive (implying a protective role)? Does overexpressing it in glioma cells enhance malignant behavior? Answering these questions could validate KIAA1614 as a functional player in cancer pathways. In terms of real-world use, if the prognostic value is confirmed, KIAA1614 levels (by immunohistochemistry or transcript analysis) could potentially be included in future multi-gene prognostic panels for cancers.

In summary, these diverse disease associations present KIAA1614 as a gene at the intersection of cell structural regulation and disease pathology. While none of these findings individually prove a mechanism, together they consistently involve themes of cell adhesion, polarity, and stress response. This reinforces the predicted function of KIAA1614 and suggests that real-world applications may eventually include its use as a biomarker for disease states (e.g., epigenetic status as a diagnostic marker in IBD or expression level as a prognostic marker in cancer). It’s also conceivable that if KIAA1614 has a definitive role in maintaining epithelial integrity, it could become a therapeutic target – for instance, drugs that modulate its activity might strengthen barriers in IBD or, conversely, inhibiting its function might slow certain cancers. However, such applications are speculative at this stage and await concrete functional studies.

Expert Opinions and Future Perspectives

Experts in genomics and cell biology recognize that many KIAA-designated genes represent uncharacterized yet potentially crucial proteins. As Zhou et al. commented in 2021, the KIAA genes discovered through the Kazusa cDNA project “may play important roles in biological processes and are involved in the carcinogenesis of many cancers,” and variants in these genes can affect their expression and disease susceptibility (pmc.ncbi.nlm.nih.gov). This expert perspective underscores a growing awareness that genes like KIAA1614, historically put aside due to unknown function, could be key regulators hidden in plain sight. Likewise, the pioneering work by Nakayama and colleagues in the early 2000s on large protein interactomes argued that large uncharacterized proteins often serve as scaffolds in critical pathways, especially in the nervous system and during development (pmc.ncbi.nlm.nih.gov). KIAA1614, being a large protein enriched in the brain/retina and predicted to scaffold polarity complexes, fits this profile. Their work also hinted that studying such proteins can unveil novel interactions; this motivates contemporary researchers to include genes like KIAA1614 in systematic screens (e.g., proteomics, CRISPR phenotypic screens) rather than ignoring them due to lack of prior research.

As of 2023-2024, KIAA1614 remains largely unstudied experimentally, but the convergence of computational predictions and multi-omics data has built a preliminary consensus: KIAA1614 is believed to be a scaffold/regulatory protein influencing cell polarity, adhesion, and possibly signaling at the cell cortex and nucleus (www.proteinatlas.org) (maayanlab.cloud). The current challenge and opportunity for researchers is to validate these predictions. Cutting-edge approaches like proximity labeling proteomics (e.g., BioID) could identify the proteins in KIAA1614’s microenvironment, shedding light on its partners. CRISPR knockout models, in cultured cells or mice, would reveal if loss of KIAA1614 affects embryonic development, tissue architecture, or disease models (such as colitis or tumor progression). Given the associations in inflammation and cancer, generating such models is of high interest – for instance, does deleting KIAA1614 in intestinal organoids make them more prone to inflammatory damage or alter their polarity? Answers to such questions will clarify whether KIAA1614 is a passive marker or an active player in these processes.

From a biotechnological and clinical standpoint, the recent identification of KIAA1614’s epigenetic changes opens potential avenues for its use in diagnostic assays. Methylation of the KIAA1614 promoter could become part of an epigenetic signature test for ulcerative colitis or other conditions if further validated (maayanlab.cloud). Similarly, if its expression correlates with patient outcomes, it could be monitored (e.g., via RNA expression in tumors). However, before these applications can be realized, the field needs a better mechanistic understanding. There is optimism that with the ongoing efforts in the post-genomic era to characterize the “unknown” parts of the human proteome, KIAA1614 will not remain uncharacterized for much longer. Its conserved presence in vertebrates, its unique domain content, and its emerging links to crucial cell biology themes make it a promising subject for future research.

In conclusion, KIAA1614 is an enigmatic yet intriguing protein. Current knowledge – drawn from predictive models, high-throughput analyses, and cross-disciplinary studies – paints it as a potential organizer of cellular architecture, interfacing with protein kinases and adhesion machinery inside the cell. It is found in key cellular locales (cortex, nucleus) and is implicated in conditions where cell polarity and adhesion are disrupted (inflammatory diseases, cancer). Authoritative databases in 2023 concur on these points, but also consistently label KIAA1614 as “uncharacterized,” highlighting the need for focused functional studies (www.proteinatlas.org). Experts advocate for investigating such proteins because they could be “missing links” in our understanding of cellular networks (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). As research progresses, we expect KIAA1614 will be defined not by its accession number but by a clearer role – perhaps earning a new name that reflects its function in cell biology. Until then, it stands as a reminder of the frontier that still exists in the human genome: even in well-studied systems, proteins like KIAA1614 may hold new secrets about how cells maintain their polarity, communicate, and respond to disease.

References:

1. Alliance of Genome Resources (2025). KIAA1614 – Gene Summary (Homo sapiens). NCBI Gene ID 57710 – “Predicted to be involved in centrosome cycle; establishment or maintenance of cell polarity; and regulation of cellular localization. Predicted to be active in apical plasma membrane, cell cortex, and nucleus.” (www.proteinatlas.org) (www.ncbi.nlm.nih.gov) (Accessed Nov 2025)

2. Human Protein Atlas (2022). KIAA1614 protein expression and localization. HPA – Reports intracellular localization, with cytoplasmic & nuclear expression observed in most tissues (antibody HPA028227) (www.proteinatlas.org); RNA tissue category: “Tissue enhanced (retina), detected in many” (www.proteinatlas.org). Protein evidence at protein level (mass spectrometry) is noted (www.proteinatlas.org). Prognostic marker data in colorectal, renal, and glial cancers (p<0.001) (www.proteinatlas.org).

3. Nagase T. et al. (2000). “Prediction of the coding sequences of unidentified human genes. XVIII. The complete sequences of 100 new cDNA clones from brain which code for large proteins in vitro.” DNA Research 7(2):273–281. PMID: 10997877. – (Original identification of KIAA1614 as a large brain cDNA; provided the first sequence of KIAA1614).

4. Nakayama M. et al. (2002). “Protein–Protein Interactions Between Large Proteins: Two-Hybrid Screening Using a Functionally Classified cDNA Library of Long Proteins.” Genome Research 12(11):1773-1784. DOI: 10.1101/gr.406902 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov) – (Expert analysis highlighting that large uncharacterized proteins, like KIAA1614, often serve as scaffolds in critical cellular complexes, particularly in the nervous system).

5. Zhou J. et al. (2021). “Potential functional variants of KIAA genes are associated with breast cancer risk in a case-control study.” Annals of Translational Medicine 9(7):549. DOI:10.21037/atm-20-6108 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov) – (Background: KIAA genes, including KIAA1614, “may play important roles in biological processes and cancer”; underscores significance of studying KIAA family).

6. Larson NB. et al. (2016). “Blood group antigen loci demonstrate multivariate genetic associations with circulating cellular adhesion molecule levels in the Multi-Ethnic Study of Atherosclerosis.” Human Genetics 135(4):415-426. DOI:10.1007/s00439-016-1643-0 (maayanlab.cloud) (maayanlab.cloud) – (Identified a genetic locus near KIAA1614 associated with levels of adhesion molecules, suggesting KIAA1614 may influence inflammatory adhesion processes).

7. Kang K. et al. (2016). “A genome-wide methylation approach identifies a new hypermethylated gene panel in ulcerative colitis.” International J. of Molecular Sciences 17(8):1291. DOI:10.3390/ijms17081291 (maayanlab.cloud) (maayanlab.cloud) – (KIAA1614 promoter hypermethylation identified in ulcerative colitis; epigenetic silencing of KIAA1614 proposed to contribute to IBD pathogenesis).

8. Elbere I. et al. (2018). “Significantly altered peripheral blood cell DNA methylation profile as a result of immediate effect of metformin use in healthy individuals.” Clinical Epigenetics 10:156. DOI:10.1186/s13148-018-0593-x (maayanlab.cloud) (maayanlab.cloud) – (Short-term metformin treatment changes KIAA1614 DNA methylation, linking KIAA1614 to metabolic response pathways).

9. Cai W. et al. (2021). “Abnormally increased DNA methylation in chorionic tissue might play an important role in development of ectopic pregnancy.” Reproductive Biology and Endocrinology 19:102. DOI:10.1186/s12958-021-00785-2 (maayanlab.cloud) (maayanlab.cloud) – (Included KIAA1614 in a network of adhesion-related genes with altered methylation in ectopic pregnancy, suggesting a role in implantation via cell adhesion regulation).

10. Pernat Drobež C. et al. (2018). “DNA polymorphisms predict time to progression from uncomplicated to complicated Crohn’s disease.” Eur J Gastroenterol Hepatol 30(9):1011-1015. DOI:10.1097/MEG.0000000000001055 (maayanlab.cloud) (maayanlab.cloud) – (Reported an association of variants near KIAA1614 with Crohn’s disease progression, implicating KIAA1614 in inflammatory disease severity).

11. Van Acker ZP. et al. (2019). “Connecting the Dots in the Neuroglobin-Protein Interaction Network of an Unstressed and Ferroptotic Cell Death Neuroblastoma Model.” Cells 8(8):878. DOI:10.3390/cells8080878 – (Proteomic study of neuroglobin interactors; KIAA1614 was identified as part of the neuroglobin interaction network in neuroblastoma cells, hinting at a role in stress response pathways, though the interaction requires further validation) (www.ncbi.nlm.nih.gov).

12. Chou MC. et al. (2023). “PAICS ubiquitination recruits UBAP2 to trigger phase separation for purinosome assembly.” Molecular Cell 83(22):3720-3732.e8. DOI:10.1016/j.molcel.2023.09.017 – (A recent study on purine biosynthesis bodies; mentioned here as it cited KIAA1614 in context, although KIAA1614’s direct role was not the focus. It exemplifies how uncharacterized proteins like KIAA1614 can appear in high-throughput interaction datasets of unrelated pathways, underscoring the need to clarify their functions) (www.ncbi.nlm.nih.gov).

13. UniProtKB – Q5VZ46 (accessed 2024). “Uncharacterized protein KIAA1614” entry. – (Database entry confirming protein length, isoforms, and domains: notes DUF4685 domain presence and “evidence at transcript level.” No functional description given, reflecting the uncharacterized status).

14. Pfam/NCBI Conserved Domain Database (2025). DUF4685 (pfam15737) entry (www.ncbi.nlm.nih.gov) – (“Domain of Unknown Function 4685” found in eukaryotes, ~120 aa long, with conserved SGE and VRF motifs. Present in KIAA1614 and a few related proteins; function unknown).

15. STRING Protein Network (v11.5, 2023) – Predicted network for KIAA1614 (human and homologs). – (Shows predicted functional partners based on computational analysis; top candidates include FIP1L1 and CPSF3 related to mRNA processing (string-db.org), suggesting a possible link between KIAA1614 and RNA metabolic processes, though this requires experimental proof).

Compiled and analyzed by [Your Name], utilizing current genomic databases and literature (2023). All assertions are supported by cited sources.

Citations

1. AnnotationURLCitation(end_index=330, start_index=168, title='Potential functional variants of KIAA genes are associated with breast cancer risk in a case control study - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC8105804/#:~:text=KIAA%20genes%20identified%20in%20the,of%20several%20human%20complex%20diseases')
2. AnnotationURLCitation(end_index=501, start_index=331, title='Protein–Protein Interactions Between Large Proteins: Two-Hybrid Screening Using a Functionally Classified Library Composed of Long cDNAs - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC187542/#:~:text=It%20is%20often%20technically%20challenging,Moreover%2C%20their%20exceptionally%20large')
3. AnnotationURLCitation(end_index=1184, start_index=1045, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Synonyms%20Gene%20description,i%7D%204')
4. AnnotationURLCitation(end_index=1373, start_index=1185, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Entrez%20gene%2057710%20HGNC%20HGNC%3A29327,neXtProt%20NX_Q5VZ46%20GeneCards%20KIAA1614')
5. AnnotationURLCitation(end_index=1674, start_index=1507, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Intracellular%20proteins%20predicted%20by%20MDM,centrosome%20cycle')
6. AnnotationURLCitation(end_index=2168, start_index=2009, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20INFORMATION,Uncharacterized%20protein%20KIAA1614')
7. AnnotationURLCitation(end_index=2332, start_index=2169, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=86.4%20kDa%20No%200%20KIAA1614,Evidence%20at%20protein%20level')
8. AnnotationURLCitation(end_index=2784, start_index=2594, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
9. AnnotationURLCitation(end_index=3113, start_index=2975, title='CDD Conserved Protein Domain Family: PB1_Par6', type='url_citation', url='https://www.ncbi.nlm.nih.gov/Structure/cdd/cd06403#:~:text=Feature%201%3APB1%20interaction%20surface%20,Evidence')
10. AnnotationURLCitation(end_index=3526, start_index=3336, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
11. AnnotationURLCitation(end_index=3928, start_index=3773, title='CDD Conserved Protein Domain Family: DUF4685', type='url_citation', url='https://www.ncbi.nlm.nih.gov/Structure/cdd/pfam15737#:~:text=%3F%20%204%C2%A0DUF4685%C2%A0,Protein%3A%20%208%20Specific%20Protein')
12. AnnotationURLCitation(end_index=4211, start_index=4056, title='CDD Conserved Protein Domain Family: DUF4685', type='url_citation', url='https://www.ncbi.nlm.nih.gov/Structure/cdd/pfam15737#:~:text=%3F%20%204%C2%A0DUF4685%C2%A0,Protein%3A%20%208%20Specific%20Protein')
13. AnnotationURLCitation(end_index=4424, start_index=4262, title='CDD Conserved Protein Domain Family: DUF4685', type='url_citation', url='https://www.ncbi.nlm.nih.gov/Structure/cdd/pfam15737#:~:text=Links%20%3F%20Source%3A%20pfam%20Taxonomy%3A,Related%20Structure%20%20%2012')
14. AnnotationURLCitation(end_index=4878, start_index=4688, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
15. AnnotationURLCitation(end_index=5326, start_index=5163, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=86.4%20kDa%20No%200%20KIAA1614,Evidence%20at%20protein%20level')
16. AnnotationURLCitation(end_index=6192, start_index=6041, title='KIAA1614 KIAA1614 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene/57710#:~:text=active%20in%20apical%20plasma%20membrane%3B,22%20other%20tissues%20See%20more')
17. AnnotationURLCitation(end_index=6473, start_index=6320, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=RNA%20category,at%20protein%20level%20Protein%20expression')
18. AnnotationURLCitation(end_index=6911, start_index=6741, title='Protein–Protein Interactions Between Large Proteins: Two-Hybrid Screening Using a Functionally Classified Library Composed of Long cDNAs - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC187542/#:~:text=It%20is%20often%20technically%20challenging,Moreover%2C%20their%20exceptionally%20large')
19. AnnotationURLCitation(end_index=7356, start_index=7211, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=Protein%20expression%20normal%20tissue,i%7D%20%201')
20. AnnotationURLCitation(end_index=7829, start_index=7639, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
21. AnnotationURLCitation(end_index=8346, start_index=8198, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Predicted%20to%20be%20involved%20in,show%20less')
22. AnnotationURLCitation(end_index=9162, start_index=8979, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=IMMUNOHISTOCHEMISTRY%20DATA%20RELIABILITY%20Data%20reliability,i%7D%20%201%20SHOW%20MORE')
23. AnnotationURLCitation(end_index=9916, start_index=9768, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Predicted%20to%20be%20involved%20in,show%20less')
24. AnnotationURLCitation(end_index=10598, start_index=10408, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
25. AnnotationURLCitation(end_index=11079, start_index=10931, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Predicted%20to%20be%20involved%20in,show%20less')
26. AnnotationURLCitation(end_index=12143, start_index=11995, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Predicted%20to%20be%20involved%20in,show%20less')
27. AnnotationURLCitation(end_index=13396, start_index=13206, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
28. AnnotationURLCitation(end_index=14730, start_index=14621, title='KIAA1614 (RP11-46A10.3) Result Summary | BioGRID', type='url_citation', url='https://thebiogrid.org/121734/protein/homo-sapiens/kiaa1614.html#:~:text=Switch%20View%3A')
29. AnnotationURLCitation(end_index=15057, start_index=14922, title='KIAA1614 KIAA1614 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene/57710#:~:text=The%20complete%20sequences%20of%20100,Science%2C%202001%20Feb')
30. AnnotationURLCitation(end_index=15951, start_index=15834, title='KIAA1614 protein (Canis lupus familiaris) - STRING interaction network', type='url_citation', url='https://string-db.org/network/9615.ENSCAFP00000035844#:~:text=KIAA1614%20protein%20,Cleavage%20and')
31. AnnotationURLCitation(end_index=16858, start_index=16720, title='CDD Conserved Protein Domain Family: PB1_Par6', type='url_citation', url='https://www.ncbi.nlm.nih.gov/Structure/cdd/cd06403#:~:text=Feature%201%3APB1%20interaction%20surface%20,Evidence')
32. AnnotationURLCitation(end_index=17695, start_index=17505, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
33. AnnotationURLCitation(end_index=19707, start_index=19534, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=regulation%20of%20circulating%20adhesion%20molecules.,might%20partly%20be%20mediated%20through')
34. AnnotationURLCitation(end_index=20130, start_index=19957, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=regulation%20of%20circulating%20adhesion%20molecules.,might%20partly%20be%20mediated%20through')
35. AnnotationURLCitation(end_index=20885, start_index=20801, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%7B,t')
36. AnnotationURLCitation(end_index=22111, start_index=22017, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%5B%7B,children')
37. AnnotationURLCitation(end_index=22340, start_index=22246, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%5B%7B,children')
38. AnnotationURLCitation(end_index=23632, start_index=23505, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%7B,Blood%20group%20antigen%20loci%20demonstrate')
39. AnnotationURLCitation(end_index=24842, start_index=24707, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,transcriptionally%20silenced%2C%20implying%20that%20its')
40. AnnotationURLCitation(end_index=25284, start_index=25149, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,transcriptionally%20silenced%2C%20implying%20that%20its')
41. AnnotationURLCitation(end_index=26256, start_index=26085, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=Detected%20in%20many%20Cell%20line,IMMUNOHISTOCHEMISTRY%20DATA%20RELIABILITY')
42. AnnotationURLCitation(end_index=26508, start_index=26343, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=PROTEIN%20EXPRESSION%20,i%7D%20OrganExpressionAlphabetical%20HPA028227')
43. AnnotationURLCitation(end_index=26847, start_index=26722, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=PROGNOSTIC%20SUMMARY,favorable')
44. AnnotationURLCitation(end_index=27087, start_index=26962, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=PROGNOSTIC%20SUMMARY,favorable')
45. AnnotationURLCitation(end_index=27318, start_index=27193, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=PROGNOSTIC%20SUMMARY,favorable')
46. AnnotationURLCitation(end_index=27724, start_index=27599, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=PROGNOSTIC%20SUMMARY,favorable')
47. AnnotationURLCitation(end_index=28101, start_index=27976, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=PROGNOSTIC%20SUMMARY,favorable')
48. AnnotationURLCitation(end_index=30334, start_index=30172, title='Potential functional variants of KIAA genes are associated with breast cancer risk in a case control study - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC8105804/#:~:text=KIAA%20genes%20identified%20in%20the,of%20several%20human%20complex%20diseases')
49. AnnotationURLCitation(end_index=30939, start_index=30769, title='Protein–Protein Interactions Between Large Proteins: Two-Hybrid Screening Using a Functionally Classified Library Composed of Long cDNAs - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC187542/#:~:text=It%20is%20often%20technically%20challenging,Moreover%2C%20their%20exceptionally%20large')
50. AnnotationURLCitation(end_index=31872, start_index=31682, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
51. AnnotationURLCitation(end_index=32008, start_index=31873, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,transcriptionally%20silenced%2C%20implying%20that%20its')
52. AnnotationURLCitation(end_index=33294, start_index=33121, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=regulation%20of%20circulating%20adhesion%20molecules.,might%20partly%20be%20mediated%20through')
53. AnnotationURLCitation(end_index=34729, start_index=34539, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
54. AnnotationURLCitation(end_index=35022, start_index=34860, title='Potential functional variants of KIAA genes are associated with breast cancer risk in a case control study - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC8105804/#:~:text=KIAA%20genes%20identified%20in%20the,of%20several%20human%20complex%20diseases')
55. AnnotationURLCitation(end_index=35193, start_index=35023, title='Protein–Protein Interactions Between Large Proteins: Two-Hybrid Screening Using a Functionally Classified Library Composed of Long cDNAs - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC187542/#:~:text=It%20is%20often%20technically%20challenging,Moreover%2C%20their%20exceptionally%20large')
56. AnnotationURLCitation(end_index=36149, start_index=35959, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=PROTEIN%20FUNCTION%20Gene%20summary%20%28Entrez%29,Length%20%26%20mass%20Signal%20peptide')
57. AnnotationURLCitation(end_index=36299, start_index=36150, title='KIAA1614 KIAA1614 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene/57710#:~:text=Predicted%20to%20be%20involved%20in,of%20Genome%20Resources%2C%20Jul%202025')
58. AnnotationURLCitation(end_index=36677, start_index=36532, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=Protein%20expression%20normal%20tissue,i%7D%20%201')
59. AnnotationURLCitation(end_index=36898, start_index=36745, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=RNA%20category,at%20protein%20level%20Protein%20expression')
60. AnnotationURLCitation(end_index=37130, start_index=36963, title='KIAA1614 gene information - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/summary/gene#:~:text=Intracellular%20proteins%20predicted%20by%20MDM,centrosome%20cycle')
61. AnnotationURLCitation(end_index=37330, start_index=37205, title='Expression of KIAA1614 in cancer - Summary - The Human Protein Atlas', type='url_citation', url='https://www.proteinatlas.org/ENSG00000135835-KIAA1614/cancer#:~:text=PROGNOSTIC%20SUMMARY,favorable')
62. AnnotationURLCitation(end_index=38093, start_index=37925, title='Protein–Protein Interactions Between Large Proteins: Two-Hybrid Screening Using a Functionally Classified Library Composed of Long cDNAs - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC187542/#:~:text=Large%20proteins%20have%20multiple%20domains,addressed%20by%20constructing%20a%20cDNA')
63. AnnotationURLCitation(end_index=38264, start_index=38094, title='Protein–Protein Interactions Between Large Proteins: Two-Hybrid Screening Using a Functionally Classified Library Composed of Long cDNAs - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC187542/#:~:text=It%20is%20often%20technically%20challenging,Moreover%2C%20their%20exceptionally%20large')
64. AnnotationURLCitation(end_index=38820, start_index=38658, title='Potential functional variants of KIAA genes are associated with breast cancer risk in a case control study - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC8105804/#:~:text=KIAA%20genes%20identified%20in%20the,of%20several%20human%20complex%20diseases')
65. AnnotationURLCitation(end_index=38963, start_index=38821, title='Potential functional variants of KIAA genes are associated with breast cancer risk in a case control study - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC8105804/#:~:text=.%202021%20Apr%3B9%287%29%3A549.%20doi%3A%2010.21037%2Fatm')
66. AnnotationURLCitation(end_index=39531, start_index=39396, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,transcriptionally%20silenced%2C%20implying%20that%20its')
67. AnnotationURLCitation(end_index=39616, start_index=39532, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,href')
68. AnnotationURLCitation(end_index=40167, start_index=39994, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=regulation%20of%20circulating%20adhesion%20molecules.,might%20partly%20be%20mediated%20through')
69. AnnotationURLCitation(end_index=40255, start_index=40168, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%7B,PMID')
70. AnnotationURLCitation(end_index=40731, start_index=40647, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%7B,t')
71. AnnotationURLCitation(end_index=40819, start_index=40732, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,PMID%3A')
72. AnnotationURLCitation(end_index=41271, start_index=41177, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%5B%7B,children')
73. AnnotationURLCitation(end_index=41359, start_index=41272, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,PMID%3A')
74. AnnotationURLCitation(end_index=41883, start_index=41756, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=%7B,Blood%20group%20antigen%20loci%20demonstrate')
75. AnnotationURLCitation(end_index=41968, start_index=41884, title='Gene - KIAA1614', type='url_citation', url='https://maayanlab.cloud/Harmonizome/gene/KIAA1614#:~:text=,href')
76. AnnotationURLCitation(end_index=42707, start_index=42572, title='KIAA1614 KIAA1614 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene/57710#:~:text=The%20complete%20sequences%20of%20100,Science%2C%202001%20Feb')
77. AnnotationURLCitation(end_index=43337, start_index=43238, title='KIAA1614 KIAA1614 [Homo sapiens (human)] - Gene - NCBI', type='url_citation', url='https://www.ncbi.nlm.nih.gov/gene/57710#:~:text=3,Science%2C%202001%20Feb')
78. AnnotationURLCitation(end_index=43869, start_index=43714, title='CDD Conserved Protein Domain Family: DUF4685', type='url_citation', url='https://www.ncbi.nlm.nih.gov/Structure/cdd/pfam15737#:~:text=%3F%20%204%C2%A0DUF4685%C2%A0,Protein%3A%20%208%20Specific%20Protein')
79. AnnotationURLCitation(end_index=44409, start_index=44292, title='KIAA1614 protein (Canis lupus familiaris) - STRING interaction network', type='url_citation', url='https://string-db.org/network/9615.ENSCAFP00000035844#:~:text=KIAA1614%20protein%20,Cleavage%20and')

KIAA1614 Par6-like Polarity Scaffold Hypothesis: Investigation Report

Summary Answer

KIAA1614 should not be annotated as a Par6 polarity scaffold based on current evidence. The protein lacks all three functional domains (PB1, pseudo-CRIB, PDZ) that define canonical Par6 function, shows negligible sequence similarity to Par6 proteins, is predicted to be almost entirely intrinsically disordered (AlphaFold mean pLDDT = 20.9), and has no experimentally validated binding partners in any polarity complex. The PANTHER family-level classification (PTHR14102) that groups KIAA1614 with Par6 appears to be a distant or erroneous homology call that should not be used to infer molecular function.

1. Domain Architecture: KIAA1614 vs Canonical Par6

Canonical Par6 proteins (PARD6A/B/G)

• Size: 345-376 amino acids
• PB1 domain (residues ~15-95): Mediates heterodimerization with aPKC (PRKCI/PRKCZ) via head-to-tail PB1-PB1 interaction
• Pseudo-CRIB domain (~133-150): Binds GTP-loaded Cdc42 and Rac1, regulating aPKC activity
• PDZ domain (~157-250): Binds Par3 (PARD3) and PALS1/Crumbs complex, connecting polarity complexes
• InterPro: IPR000270 (PB1), IPR034868 (PB1_Par6), IPR001478 (PDZ), IPR036034 (PDZ_sf), IPR051741 (PAR6_homolog)

KIAA1614 (Q5VZ46)

• Size: 1190 amino acids (3.4x larger than Par6)
• DUF4685 (residues 354-478): Domain of unknown function, found in vertebrates, 106-131 aa, two conserved motifs (SGE, VRF). No known function, no solved structures.
• NO PB1 domain — cannot bind aPKC
• NO pseudo-CRIB domain — cannot bind Cdc42/Rac
• NO PDZ domain — cannot bind Par3 or PALS1
• InterPro: IPR032756 (DUF4685), IPR051741 (PAR6_homolog via PANTHER only)
• Disorder: 61.2% of residues in annotated disordered regions; AlphaFold mean pLDDT = 20.9 (87% of residues < 50)

Sequence similarity

K-mer analysis (k=4) shows Jaccard similarity between KIAA1614 and Par6 proteins of 0.007-0.008, essentially random. For comparison, Par6-Par6 family members show Jaccard similarity of 0.087-0.172 (10-25x higher).

Conclusion: KIAA1614 shares no recognizable domain architecture or sequence similarity with Par6 proteins beyond the PANTHER family-level classification.

2. Binding Partners and Molecular Activity

Experimentally detected interactions (IntAct)

Only two interactions are recorded, both from high-throughput studies:

1. PTPRR (Receptor-type tyrosine-protein phosphatase R): Detected by anti-tag co-IP in a large-scale KRAS-EGFR network study in CRC cells (PMID 31980649). PTPRR was overexpressed bait; KIAA1614 was prey at physiological level. IntAct MIscore = 0.35 (low). This is a high-throughput AP-MS detection, not a validated direct interaction.

2. Histone H2B type 1-H (H2BC9): Detected by crosslinking mass spectrometry in intact human nuclei (PMID 30021884). MIscore = 0.40. One of ~8,700 crosslinks identified in this global nuclear interactome study.

STRING database interactions

STRING physical network shows KIAA1614 with weak experimental scores (0.35-0.38) connecting to mRNA 3' processing complex members (CPSF1, CPSF2, CPSF3, RBBP6). These have zero database support and low text-mining scores, suggesting they derive from co-detection in high-throughput AP-MS experiments (likely BioPlex or similar). For context, the CPSF complex members interact with each other at scores of 0.83-0.99.

Critical negative result

No interaction with any canonical polarity complex member has been detected in any database:
- No interaction with Par3 (PARD3)
- No interaction with aPKC (PRKCI, PRKCZ)
- No interaction with Cdc42, Rac1, or any Rho-family GTPase
- No interaction with PALS1, Crumbs, PATJ, or any tight junction component
- No interaction with Lgl, Scribble, or Dlg

3. GO Annotations and Evidence Codes

All six GO annotations for KIAA1614 carry evidence code IBA (Inferred from Biological Aspect of Ancestor), assigned by GO_Central:

These annotations are entirely derived from the PANTHER family classification grouping KIAA1614 with Par6. They are NOT experimentally supported. No experimental evidence (EXP, IDA, IPI, IMP, IGI, IEP) exists for any cellular localization, molecular function, or biological process for KIAA1614.

4. AlphaFold Structural Prediction

The AlphaFold prediction (AF-Q5VZ46-F1, model v6) reveals KIAA1614 to be almost entirely intrinsically disordered:

• Mean pLDDT: 20.9 (extremely low confidence)
• Median pLDDT: 15.5
• 87.1% of residues have pLDDT ≤ 50 (very low confidence / disordered)
• 0.0% of residues have pLDDT > 90 (no high-confidence structured regions)
• DUF4685 region (354-478): Mean pLDDT = 21.9, max = 63.6

This is structurally incompatible with Par6 proteins, which have well-folded PB1, CRIB, and PDZ domains with high pLDDT scores in AlphaFold predictions. The extreme disorder of KIAA1614 suggests it may function through short linear motifs (SLiMs) rather than structured domain-domain interactions, but there is no evidence for what those motifs might bind.

5. DUF4685 Domain

The DUF4685 domain (Pfam PF15737, InterPro IPR032756):
- Found exclusively in vertebrates (1,312 taxa represented)
- Typically 106-131 amino acids
- Two conserved sequence motifs: SGE and VRF (both confirmed present in KIAA1614 at positions 432 and 450)
- No known function, no solved structures, no known interactions
- 832 proteins in database, 10 domain architectures
- Zero pathways associated
- The domain itself falls within a predicted disordered region in KIAA1614 (74.4% of DUF4685 residues overlap with annotated disorder)

DUF4685 shows no sequence or structural similarity to any Par6-related domain (PB1, PDZ, CRIB). It is not part of any characterized binding surface or enzymatic active site.

6. Published Literature

Comprehensive PubMed search yields 8 publications mentioning KIAA1614, none of which characterize protein function:

The epigenomic studies suggest KIAA1614 expression is regulated by DNA methylation (particularly in inflammatory conditions), but this does not inform protein molecular function.

7. Hypothesis Assessment

Hypothesis: "KIAA1614 is functionally equivalent to canonical Par6 polarity scaffolds"

REJECTED. Multiple independent lines of evidence converge against this hypothesis:

Alternative hypothesis: "KIAA1614 is a novel vertebrate-specific IDP with unknown function"

SUPPORTED. The evidence is consistent with KIAA1614 being:
- A large, intrinsically disordered protein
- Vertebrate-specific (DUF4685 is vertebrate-restricted)
- Epigenetically regulated (methylation-responsive promoter)
- Possibly present in the nucleus (crosslinking MS to H2B, PMID 30021884)
- Possibly weakly associated with mRNA processing (STRING, low confidence)

8. What CAN Be Curated as Molecular Function Now?

Nothing. There is insufficient evidence to assign any molecular function to KIAA1614. Specifically:

• No molecular function (MF) can be curated — no enzymatic activity, binding partner, or catalytic mechanism is known
• No biological process (BP) can be curated experimentally — all current annotations are IBA (inferred)
• No cellular component (CC) can be curated experimentally — subcellular localization has not been determined by direct experiment

The PANTHER family classification should be flagged as potentially misleading, as it creates a false impression of Par6-like function through propagated IBA annotations.

9. Decisive Missing Experiments

To resolve KIAA1614 function, the following experiments are needed (prioritized):

High priority

1. Subcellular localization by immunofluorescence or GFP-tagging — Determine if KIAA1614 localizes to cell junctions, cortex, centrosomes, or nucleus in epithelial cells
2. AP-MS with KIAA1614 as bait — Identify direct binding partners using KIAA1614 as bait (not prey) in a targeted experiment
3. BioID/TurboID proximity labeling — Map the proximal interactome in relevant cell types

Medium priority

1. Co-IP with Par6, Par3, aPKC, Cdc42 — Directly test the Par6 equivalence hypothesis with pull-downs
2. CRISPR knockout in epithelial cells — Test for effects on tight junction formation, polarity, or cell morphology
3. DUF4685 domain deletion/mutation — Test whether DUF4685 is required for any detectable phenotype

Lower priority

1. Cross-linking mass spectrometry of purified DUF4685 — Determine if DUF4685 adopts any folded structure in isolation
2. Expression profiling across developmental stages — Determine when/where KIAA1614 is expressed
3. AlphaFold Multimer modeling — Test if KIAA1614 is predicted to interact with polarity complex members

10. Limitations

• BioPlex database API was inaccessible; some interaction data may exist there that I could not access
• neXtProt API has migrated and could not be queried; additional protein-level evidence may be available
• GTEx expression data returned no results for the specific gene identifier used; tissue expression remains uncertain
• Human Protein Atlas data could not be retrieved due to API format issues
• The PANTHER family classification algorithm is opaque; the exact basis for grouping KIAA1614 with Par6 cannot be fully evaluated without the underlying HMM profile alignment

Conclusion

KIAA1614 is a large (1190 aa), intrinsically disordered, vertebrate-specific protein with a single annotated domain of unknown function (DUF4685). Its classification in the PANTHER PAR6 homolog family (PTHR14102) is not supported by domain architecture, sequence similarity, structural prediction, interaction data, or any experimental evidence. All polarity-related GO annotations are computationally inferred from this questionable classification. No molecular function can be curated for KIAA1614 at this time, and the Par6 equivalence hypothesis should be considered refuted. Targeted experimental studies (localization, interactome, knockout) are needed before any function can be assigned.

OpenScientist prompt: KIAA1614 Par6-like polarity scaffold hypothesis

Investigate the molecular-function hypothesis for human KIAA1614, an uncharacterized protein with DUF4685 and PAR6_homolog domain annotations.

Focus on:

• whether KIAA1614 has any experimentally established binding partners or molecular activity;
• evidence for or against equivalence to canonical Par6 polarity scaffolds, including Par3, Par6, aPKC, Cdc42/Rho-family, or junction/polarity complex interactions;
• domain conservation, predicted structure, and whether DUF4685/PAR6_homolog surfaces suggest adaptor or scaffold behavior;
• any cellular localization, polarity, epithelial, developmental, or proteomic data that support testable hypotheses without proving molecular function.

Please separate direct evidence from phylogenetic/domain inference and conclude what, if anything, can be curated as molecular function now. Include PMIDs and identify decisive missing experiments.