An extensive family of small GTP-binding proteins (rab, rac, rad, rag, ral, ran, rheb, rho, gem, kir, ric, rin, rit, Ypt). The rab subfamily is involved in regulation of membrane trafficking; rac and rho regulate the cytoskeleton. The rad subfamily (not related to rad proteins) includes rad (ras associated with diabetes), gem (immediate early gene expressed in mitogen-stimulated T cells), and kir (tyrosine kinase-inducible ras-like) and are regulated themselves by serine kinases. The ragGTPases are linked to the mTOR system, ral has been associated with oncogenic transformation, and ran is involved in traffic into the nucleus. Rheb is enriched in brain. Rin, ric, and rit lack prenylation sequences and are well conserved between Drosophila and humans; rin is confined to neuronal cells. Ypts are the yeast homologues, of which eleven are known.
Subjects: Medicine and Health.