Localization of GTPase-activating protein-(GAP) like immunoreactivity in mouse cerebral regions

GTPase-activating protein is known to regulate the conversion between ras-G TP and ras-GDP. We studied the basal expression of GTPase-activating protei n-like immunoreactivity in mouse cerebral regions using a polyclonal anti-G TPase-activating protein antibody. Cells with GTPase-activating protein-lik e immunoreactivity were distributed in frontal cortical layers TV and V, an d in the parietal cortex, piriform cortex, amygdaloid area, septum, lateral thalamus, and hypothalamus. The GTPase-activating protein-like immunoreact ivity was also observed in fiber-like structures in the caudate putamen, st ria terminalis, internal capsule, and medial forebrain bundle, and around C A2 pyramidal cells in Ammon's horn. These results imply that GTPase-activat ing protein is constitutively expressed in mouse brain regions and may have physiological functions in specific neuronal pathways in the brain.