IDENTIFICATION OF A NOVEL PROTEIN CONTAINING 2 C2 DOMAINS SELECTIVELYEXPRESSED IN THE RAT-BRAIN AND KIDNEY

We have isolated and characterized a rat brain cDNA clone which encode s a new protein of 474 amino acids in length which contains two C2 dom ains structurally homologous to those present in synaptotagmins. The o verall amino acid identity in C2 domains between this protein and the synaptotagmins is 36-44%, This protein also contains 3 putative consen sus sequences for phosphorylation by cAMP-dependent protein kinase, RN A blot hybridization revealed a 3.0 kb transcript abundantly expressed only in the rat brain and the kidney, Thus, we called this brain/ kid ney protein (B/K), In situ hybridization and Northern blot analyses sh owed that the B/K transcript was found in forebrain including the olfa ctory bulb, cerebral cortex, hippocampus, and hypothalamus, In the kid ney, high levels of B/K transcript mere expressed in the papillary reg ion of the inner medulla, the inner stripe of the outer medulla and th e cortex, The selective expression in forebrain and kidney suggests th at B/K may be involved in similar cAMP-dependent processes at these ve ry different sites.