DYDC1

Model summary

A soluble dimeric scaffold that concentrates and stabilizes axonemal protein assemblies required for motile cilia and sperm flagella. By using an N-terminal docking module to dimerize and recruit partners, it organizes multiprotein complexes that support assembly and maintenance of the axoneme, thereby sustaining rhythmic bending and efficient sperm motility. A cytoplasmic pool supplies components that are enriched at the axoneme, where the scaffold coordinates regulatory and structural factors that tune dynein-driven beating.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The N-terminus harbors IPR049630 (DPY30 domain-containing protein-like, dimerization/docking domain, residues 2–43), a compact helical module that enforces obligate dimerization and provides a docking surface for partner proteins. This core is reinforced by IPR007858 (Dpy-30 motif, conserved site, residues 3–41), which overlaps the same N-terminal region and marks a conserved docking/dimer interface. Encompassing nearly the full length is IPR037856 (Sdc1/DPY30 family, residues 4–158), indicating a soluble, non-enzymatic scaffold class whose hallmark is to organize higher-order assemblies through dimeric adaptors. The ordered layout—an N-terminal dimerization/docking module embedded within a broader Sdc1/DPY30 scaffold—causes multivalent protein association rather than catalysis, directly supporting GO:0005515 protein binding as the molecular function.

2. 02

   A dimeric docking scaffold of this class typically nucleates macromolecular complexes that require precise spatial organization.

   In the context of motile cilia and flagella, such scaffolds stabilize axonemal assemblies that control beat mechanics. The explicit presence of a high-affinity docking domain predicts selective recruitment to the axoneme—the core microtubule-based scaffold of cilia and flagella—thereby driving the biological role captured by GO:0030317 flagellated sperm motility. By stabilizing axonemal protein networks and coordinating assembly, the scaffold ensures efficient waveform propagation and thus motility.

3. 03

   The cellular context follows from this assembly logic.

   A soluble dimeric adaptor without transmembrane segments is expected to reside in the cytoplasm and traffic onto cytoskeletal structures. Its docking propensity and family signature align with accumulation at the axoneme, consistent with GO:0005930 axoneme, while a soluble pool in the cytoplasm (GO:0005737 cytoplasm) supplies components for assembly and turnover. This dual localization—cytoplasmic reservoir and axonemal enrichment—matches the functional demands of ciliary assembly and maintenance.

4. 04

   Mechanistically, the N-terminal dimerization/docking domain seeds a bivalent platform that binds multiple axonemal partners, concentrating them into a stable lattice along doublet microtubules.

   This architecture likely coordinates regulatory complexes that tune dynein-driven sliding and radial spoke–central pair signaling, thereby sustaining rhythmic bending. From this, I hypothesize interactions with intraflagellar transport adaptors and axonemal regulators: intraflagellar transport particles (e.g., IFT-B components) to deliver cargo; dynein regulatory complex and radial spoke proteins to modulate force production; and central pair/axonemal assembly factors to maintain structural integrity. Together, these associations explain how a soluble DPY30-like scaffold converts dimeric docking energy into robust axonemal assembly and sustained sperm flagellar motility.