IDENTIFICATION OF 2 HIGHLY HOMOLOGOUS PRESYNAPTIC PROTEINS DISTINCTLYLOCALIZED AT THE DENDRITIC AND SOMATIC SYNAPSES

Through screening of a murine brain cDNA library, we have isolated two brain specific cDNAs encoding highly homologous proteins, named 921-L and 921-S, comprised of 134 amino acids with 80% identity. Immunohist ological study with the mAbs raised against the bacterially expressed 921 proteins showed that 921-L protein is distributed at the dendritic region and 921-S at the neuronal somatic surface. Immune-electron mic roscopic study revealed that both 921 proteins are localized at the pr esynaptic terminal, indicating that the 921 proteins are differentiall y expressed at the dendritic and somatic presynapses.