CCDC17

Model summary

A soluble, coiled-coil–rich scaffold that assembles multiprotein complexes to nucleate and stabilize microtubules, thereby building and maintaining the mitotic spindle. By oligomerizing through central and C-terminal assembly modules, it concentrates nucleation and bundling factors at centrosomes and along spindle microtubules, enhancing polymerization and bundle formation to secure spindle integrity during cell division.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The polypeptide carries IPR060405 (CCDC17, middle coiled-coil domain, residues 240–316) followed by IPR060404 (CCDC17, C-terminal domain, residues 399–565). These structured modules sit within the broader family signature IPR038800 (Coiled-coil domain-containing protein 17 family, residues 8–620), which blankets nearly the entire sequence. The tandem arrangement of a central coiled-coil followed by a defined C-terminal scaffold strongly favors an elongated, oligomerization-competent rod that assembles higher-order complexes. Coiled-coils create avid, multivalent interfaces that drive selective protein binding and cytoskeletal tethering; this architecture causally supports GO:0005515 protein binding as the primary molecular function.

2. 02

   A coiled-coil scaffold positioned internally and terminating in a second assembly domain is well-suited to organize microtubule nucleation and bundling machinery.

   Such scaffolds typically concentrate γ-tubulin ring complexes and plus-end regulators at microtubule organizing centers, thereby promoting GO:0010968 regulation of microtubule nucleation and GO:0031116 positive regulation of microtubule polymerization. By stabilizing lateral contacts and aligning multiple protofilaments, the same architecture drives GO:0001578 microtubule bundle formation. These molecular activities collectively build and maintain the bipolar apparatus required for mitosis, directly feeding into GO:0007052 mitotic spindle organization.

3. 03

   The spatial logic of this scaffold points to a centrosomal and spindle-associated locale.

   Coiled-coil assemblies that regulate nucleation and bundling typically accumulate at the microtubule organizing center and along spindle microtubules. This predicts residence at the GO:0005813 centrosome and dynamic redistribution to spindle structures during mitosis. The absence of transmembrane features and the soluble, oligomeric nature of the domains further support a cytoplasmic, cytoskeleton-associated distribution that concentrates at centrosomes and spindle poles.

4. 04

   Mechanistically, the middle coiled-coil (IPR060405) likely mediates homo-oligomerization and initial complex assembly, while the C-terminal domain (IPR060404) provides specificity for centrosomal and spindle partners.

   This bipartite scaffold can recruit γ-tubulin ring complex subunits and pericentriolar matrix constituents to seed and sustain microtubule arrays, while simultaneously engaging bundling and stabilization factors. I therefore hypothesize interactions with γ-tubulin and its anchoring partners (TUBGCPs and GCPs), pericentriolar matrix organizers (pericentrin and CDK5RAP2), and spindle assembly factors (NuMA and TPX2). Through these assemblies, the protein nucleates and organizes microtubules, bundles arrays into higher-order structures, and ensures robust mitotic spindle formation and integrity.