UNC-108 (Rab2) protein is present in the somas and processes of neurons but is not concentrated at synapses. (A) The head region of an adult animal is coimmunostained with an antibody against UNC-108 (green) and UNC-17, a cholinergic synaptic vesicle marker (red; Duerr et al., 2001). Asterisks mark cell somas expanded in B. (B) Expanded view of neuronal cell somas from A showing areas of concentrated UNC-108 immunoreactivity in neuronal cell somas. Arrows indicate regions of especially highly concentrated UNC-108 surrounding subcellular structures. The bracketed region indicates lower concentrations of UNC-108 irregularly distributed in the cytoplasm. (C) The vulval region of an adult animal coimmunostained with an antibody against UNC-108 (green) and UNC-17 (red). (D) An N-terminal GFP-tagged version of UNC-108 is highly enriched in small subregions (arrows) within DA6 and DB6 neuronal cell somas. The genotype of the transgene is ceEx231 [unc-129::GFP–UNC-108, unc-129::RFP–SNB-1]. Arrowheads point to non–Golgi-related GFP–UNC-108 fluorescence in the dendrite. (E and F) GFP-tagged UNC-108 is largely excluded from synaptic vesicle clusters. Two regions of the dorsal cord containing axons of the DA and DB motor neurons. GFP–UNC-108 is green, and synaptic vesicle clusters marked with RFP–SNB-1 (Sieburth et al., 2005) expressed from the same promoter are red.