LRRC72

Model summary

A human LRR-based scaffold that assembles and tunes the ciliary apparatus. Its curved repeat architecture concentrates binding partners to stage axoneme construction and to regulate microtubule-driven transport that calibrates cilium motility. By operating at centriolar satellites and adjacent centrosomal/ciliary territories, it coordinates cargo handoff toward the basal body, thereby promoting axoneme assembly and controlling ciliary movement through multivalent protein interactions.

Predicted Gene Ontology terms

1. 01

   I begin with the InterPro architecture.

   The core scaffold is a leucine-rich repeat (LRR) array: IPR032675 (Leucine-rich repeat domain superfamily, residues 38–197) encompasses the central solenoid that mediates avid, shape-complementary protein–protein interactions. Two internal repeats are explicitly annotated—IPR001611 (Leucine-rich repeat, residues 68–89) and IPR001611 (Leucine-rich repeat, residues 90–111)—which together form the curved binding surface typical of LRR solenoids that nucleate multiprotein assemblies rather than catalysis. This LRR core sits within a lineage-specific envelope, IPR042655 (Leucine-rich repeat-containing protein 72 family, residues 26–281), which defines a dedicated assembly factor. The ordered layout—family-defining region flanking an LRR superfamily core with internal repeats—creates a high-affinity adaptor platform that causes robust protein binding and scaffolding, aligning with GO:0005515 protein binding as the molecular function.

2. 02

   An LRR scaffold of this type is well-suited to organize cytoskeletal and membrane-trafficking modules.

   The biological processes inferred from this architecture converge on ciliogenesis and ciliary control. First, the scaffold’s avid binding capacity supports GO:0035082 axoneme assembly: by clustering axonemal precursors and transport adaptors, the LRR array can seed and stabilize the assembly of the axonemal microtubule core. Second, the same binding platform can tune motility pathways—by recruiting dynein–kinesin regulators and IFT machinery—thus driving GO:0060632 regulation of microtubule-based movement. Third, by coordinating assembly and transport within the ciliary compartment, it modulates the emergent behavior of the organelle, consistent with GO:0003352 regulation of cilium movement. Together, these processes explain how a non-enzymatic LRR scaffold orchestrates both assembly and functional tuning of the cilium.

3. 03

   Cellular placement follows from the assembly logic.

   The presence of GO:0034451 centriolar satellite points to a pericentriolar, PCM1-positive satellite network that traffics cargoes toward the basal body and cilium base. An LRR scaffold that binds multiple partners is well-suited to concentrate at centriolar satellites to stage axoneme assembly and cargo delivery. This localization naturally extends to the broader centrosomal and ciliary territories, where the scaffold can couple satellite trafficking to axonemal construction and motility control.

4. 04

   Mechanistically, I hypothesize that the LRR solenoid forms a hub that captures centriolar satellite components and ciliary assembly factors, channeling them toward the basal body and along the axoneme.

   By stabilizing complexes that regulate microtubule-based transport and dynein-driven motility, the scaffold ensures efficient axoneme assembly and calibrated ciliary beating. Likely partners include satellite organizers (e.g., PCM1 and CEP131), dynein–dynactin adaptors, and IFT-B components that collectively drive cilium assembly and movement.