CLHC1 is a 586-amino-acid, clathrin-heavy-chain-related protein containing TSNAXIP1_N, ARM-type-fold, and clathrin-heavy-chain-linker domain assignments plus a predicted coiled-coil. It is substantially shorter than canonical clathrin heavy chains and has not been shown to assemble clathrin coats or mediate vesicle trafficking. Two splice isoforms are documented, with isoform 2 lacking the N-terminal 122 residues. Cell-atlas expression is enriched in early spermatids and clusters with ciliated-cell genes, while antibody imaging reports centrosomal and nucleolar fibrillar-center localization; these leads have not yet been tied to a physiological role. Proteome-scale binary-interaction mapping detected interactions with LMO2, SGF29, and CEP170P1, but CLHC1's molecular activity, native complex, and core biological process remain unknown.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005515 protein binding | IPI PMID:25416956 A proteome-scale map of the human interactome network. | MARK AS OVER ANNOTATED | Summary: The three source GOA rows report CLHC1 binary interactions with LMO2, SGF29, and CEP170P1 from the proteome-scale human interactome map. These partner-level observations are useful interaction context, but the consolidated generic protein-binding term does not describe a specific CLHC1 molecular activity. Reason: GO:0005515 is too broad to represent a core molecular function. The three high-throughput partners do not define a coherent native complex or a more specific binding class, and no focused biochemical or physiological study establishes what CLHC1 does. The interaction observations should remain available at partner level, but no replacement GO molecular-function term is justified and no clathrin-coat or vesicle-trafficking activity should be inferred from the protein name/domain alone. Supporting Evidence: PMID:25416956 A proteome-scale map of the human interactome network. file:human/CLHC1/CLHC1-uniprot.txt Q8NHS4; Q96L14: CEP170P1; NbExp=3 file:human/CLHC1/CLHC1-uniprot.txt Q8NHS4; P25791: LMO2; NbExp=3 file:human/CLHC1/CLHC1-uniprot.txt Q8NHS4; Q96ES7: SGF29; NbExp=3 |
Loading supporting content…
Download this section (compressed HTML)Q: Which of the LMO2, SGF29, and CEP170P1 binary interactions occur with endogenous CLHC1 in a physiological cell type, and do they define a stable complex?
Q: Does the ciliated-cell and early-spermatid expression pattern reflect a direct role in cilium or sperm-flagellum assembly/function, or only correlated expression?
Q: Does loss of the N-terminal 122 residues in isoform 2 alter CLHC1 localization, partner selection, stability, or biological activity?
Experiment: Endogenously tag CLHC1 in differentiated human airway epithelial cells and a testis-derived model, perform affinity purification-mass spectrometry and proximity labeling, and validate candidate interactions by reciprocal co-immunoprecipitation. Explicitly test LMO2, SGF29, and CEP170P1 and compare both CLHC1 isoforms.
Hypothesis: CLHC1 forms a reproducible endogenous complex distinct from generic high-throughput binary-interaction noise.
Type: Endogenous interactome mapping and orthogonal interaction validation
Experiment: Generate CLHC1 knockout and isoform-specific rescue lines in an air-liquid-interface multiciliated airway model and, where feasible, a human spermatid differentiation model. Quantify ciliogenesis, axoneme ultrastructure, ciliary beat, and relevant cell-differentiation phenotypes while controlling for general fitness effects.
Hypothesis: CLHC1 contributes to cilium or flagellum biogenesis/function in cell types where its transcript is enriched.
Type: CRISPR loss-of-function and rescue phenotyping
Experiment: Compare endogenous knock-in fluorescent tagging, knockout-controlled antibody staining, and biochemical fractionation across ciliated and non-ciliated cells; follow CLHC1 through the cell cycle and ciliated-cell differentiation.
Hypothesis: The reported centrosomal and nucleolar fibrillar-center localizations represent endogenous CLHC1 rather than antibody or overexpression artifacts.
Type: Endogenous localization and reagent validation
What is not known — curated, literature-grounded statements of the open unknowns (the inverse of core functions).
Gap: CLHC1's direct molecular activity, physiological interaction partners or native complex, and the biological process in which it acts are undetermined.
OPEN BIOLOGYCURATION WHOLLY_DARK
What is known: CLHC1 is an expressed 586-aa protein with defined domain architecture and three proteome-scale binary interaction calls, but these observations do not establish a specific activity or pathway.
Significance: Resolving this gap is necessary to replace the uninformative protein-binding annotation with a specific molecular function and to determine whether the ciliated-cell/testis expression pattern reflects a ciliary or reproductive role.
What would resolve it: Endogenous interaction mapping and loss-of-function/rescue studies in relevant human cell contexts, coupled to biochemical reconstitution of validated partners, would establish activity, complex membership, and process.
Provenance (the field's own admissions):
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)