1G5 - A CALMODULIN-BINDING, VESICLE-ASSOCIATED, PROTEIN KINASE-LIKE PROTEIN ENRICHED IN FOREBRAIN NEURITES

We have characterized cDNA crones of 1G5, an mRNA highly enriched in t he mammalian forebrain that encodes a 504-residue protein found in ass ociation with perikaryal membranes and neurites. The protein, which ac cumulates predominantly postnatally, is associated with vesicles in bo th axons and dendrites. The sequence of the 1G5 protein highly resembl es those of protein kinases with serine/threonine specificity; however , although most residues universally conserved among protein kinases a re present, a few signature residues are absent from the 1G5 protein. Furthermore, although recombinant 1G5 protein binds calmodulin in the presence of calcium, it lacks kinase activity with a sample substrate.