~all neurons. Immunoreactivity was detected in the synaptic-rich regions of the nervous system in a pattern similar to the distribution of the C. elegans synaptic vesicle membrane protein synaptotagmin. Specifically, the nerve ring, ventral nerve cord, and dorsal nerve cord showed the highest immunoreactivity.
rab-3 expression also was observed in the pharyngeal nervous system. Detectable levels of RAB-3 were rarely observed in neuronal cell bodies, dendrites of sensory neurons, or the commissural tracts of motor neurons. In contrast to synaptotagmin, RAB-3 protein was not observed at significant levels in the gonadal
uv1 neurosecretory cells. Additionally, RAB-3 was not observed in muscle, hypodermis, or intestinal tissue. Analysis of transgenic animals carrying the
rab-3::lacZ reporter construct pMG122 confirmed that the gene is expressed in most, if not all, neurons but is not expressed in other tissues.