Figure 1. UNC-108/Rab2 functions in the nervous system of C. elegans. (A) The amino acid sequence of the UNC-108 protein is shown. Alleles are marked with arrows pointing to the amino acid transition for each missense mutation. The conserved G1-G5 motifs involved in GTP binding are highlighted in blue. The solid line below the sequence represents the 66-amino acid deletion in the
nu415 allele. (B) An anti-mouse RAB2 antibody (Santa Cruz Biotechnology) detects UNC-108 as a 23-kDa band on a Western blot of extracts prepared from wild-type worms but not from
unc-108(
nu415) mutants. (C) The number of body bends per 30 s was counted for wild-type,
unc-108(
nu415), and
unc-108(
nu415) animals expressing FLAG-tagged UNC-108 under the following promoters:
snb-1 (pan-neuronal Synaptobrevin),
glr-1,
unc-17 (cholinergic motorneurons), and
myo-3 (body wall muscle) (n = 20 for each).
unc-108(
nu415) animals show a 54% decrease in body bends as compared with wild-type control worms (p < 0.0001). Expression of FLAG-tagged UNC-108 under the
glr-1,
unc-17, and
myo-3 promoters did not rescue the locomotion defect in
unc-108(
nu415) mutants. Expression of FLAG-tagged UNC-108 under the
snb-1 promoter restored locomotion to 86% of that of wild type (p = 0.014 compared with wild-type, p < 0.0001 compared with
nu415) in
unc-108(
nu415) mutant worms. (D) A 2.5-kb promoter fragment of the
unc-108 gene was cloned upstream of GFP followed by the
unc-54 3' UTR. Stage three larval (L3) worms expressing this transcriptional reporter construct were imaged. Bar, 50 µm. Error bars indicate SEM. **p < 0.001, statistical significance of compared with wild type; ##p < 0.001 indicates statistical significance compared with
unc-108(
nu415) (Student's t test).