unc-108 encodes a homologue of human Rab2 and controls locomotion and cell corpse removal. (A) Position of the unc-108 locus on chromosome I. Among the cosmid clones tested (lines with bars on both sides), F53F10 rescued the n3263 phenotypes. (B) Structure of unc-108. Exons (boxes) are connected by introns (lines). The coding region is shown in black and the untranslated region is in gray. Positions of mutations are indicated. (C) Alignment of human Rab2A and UNC-108. PM1–3, motifs that bind the phosphate groups of GTP and the Mg²⁺ cofactor; G1–G3, motifs that contact the guanine base; switch 1 and 2, domains predicted to undergo dramatic conformational change upon GTP hydrolysis; RabF, signature residues conserved among Rab family members (Pereira-Leal and Seabra, 2000, 2001). The positions and amino acid substitutions resulting from the five point mutations are indicated. Pre, prenylation site. (D and E) Molecular lesions and quantification of phenotypes in the indicated genetic backgrounds. The numbers of cell corpses are reported as mean ± SD (n = 15). (asterisks) Data from Simmer et al. (2003).