DIFFERENTIAL REGULATION IN THE AVIAN SONG CONTROL-CIRCUIT OF AN MESSENGER-RNA PREDICTING A HIGHLY CONSERVED PROTEIN RELATED TO PROTEIN-KINASE-C AND THE BCR ONCOGENE

An RNA identified by differential cDNA cloning (HAT-2) is highly enriched in canary forebrain in areas associated with the control of complex learned behaviors and higher perceptual processes. The nucleotide sequence predicts a protein that is 96% identical to the product of the n-chimaerin gene isolated from human brain and contains two identifiable domains suggesting a novel role in signal transduction processes. One domain is similar to the sequence in protein kinase C which mediates diacylglycerol binding and regulation. The second domain is similar to a portion of BCR, a GTPase-activating protein encoded by the breakpoint cluster region gene. In male canaries examined during the song season, HAT-2 RNA shows variable expression within the song control circuit, and is notably less abundant in the three nuclei which concentrate androgens (HVC, RA and L-MAN). A fundamental function in the vertebrate forebrain and a possible role in the regulation of neural plasticity are suggested by the conserved structure and pattern of expression of this gene in the brain.