RIC8A

RIC8 guanine nucleotide exchange factor A

Ensembl:
ENSG00000177963
UniProt:
Q9NPQ8
OMIM:
609146
Synonyms:
RIC8, Synembryn-A, Synembryn, Chaperone Ric-8A, SYNEMBRYN

Cilia effects upon perturbation of RIC8A

Cilia number / % ciliated:
Decreased cilia number
Loss-of-function effect:
Impaired ciliogenesis
Overexpression effect:
Unknown

Ciliogenesis screen results (1 screen)

  • Wheway et al. 2015 (siRNA) [siRNA]: Ciliogenesis Defect (z=-3.97) PMID:26167766

Phenotypes

Mouse phenotype:
persistence of hyaloid vascular system

Subcellular localization

cilia, cytosol, Plasma membrane, Cytosol

Functional category

  • G protein signaling
  • Cilium signaling
  • Ciliary assembly/disassembly
  • Cilia–cytoskeleton/adhesion links

Function

RIC-8 is a highly conserved non-canonical guanine nucleotide exchange factor that binds monomeric GDP-bound Galpha subunits and catalyses GTP exchange independently of GPCRs. Mammals encode two paralogs (RIC8A: Galpha-i/q/12/13; RIC8B: Galpha-s/olf). C. elegans RIC-8 localizes to the inversin compartment of channel cilia and depends on intraflagellar transport for ciliary entry, with an RVxP motif and intact transition zone required for proper distribution; loss of ric-8 in C. elegans reduces wing cilia length in AWA, AWB, AWC sensory neurons. Campagna et al. 2026 reported that human RIC8A and RIC8B are required for ciliogenesis in RPE-1 cells (preprint figures pending direct review).

Model organism evidence

Homo sapiens (RPE-1 cells) (1 reference)

Human RIC8A is required for ciliogenesis in RPE-1 cells; depletion reduces ciliated cell percentage (Campagna et al. 2026, bioRxiv preprint pending peer review).

PMIDs: 41727026

C. elegans (1 reference)

C. elegans RIC-8 localizes to the inversin compartment (InvC) of channel cilia and depends on intraflagellar transport for ciliary entry. An RVxP motif and intact transition zone are required for proper ciliary distribution.

Loss of ric-8 in C. elegans reduces wing cilia length in AWA, AWB, and AWC sensory neurons and disrupts heterotrimeric G-protein signaling at cilia.

PMIDs: 37793942