Dynamic properties of the Ca2+/calmodulin-dependent protein kinase in Drosophila: identification of a synapsin I-like protein.

Visual adaptation with blue light induces a change in a special light/dark choice behavior in Drosophila. On the molecular level adaptation induces long-term modulation of the in vitro autophosphorylation capacity of a Ca2+/calmodulin-dependent protein kinase. Here I describe a Drosophila phosphoprotein that is a substrate of this protein kinase. The molecular mass and phosphopeptide composition of this protein are similar to those of rat synapsin I. Furthermore, the Drosophila protein shows immunological cross-reactivity with monoclonal antibodies against rat synapsin I. I conclude that this 86-kDa protein in Drosophila is homologous to the vertebrate synapsin I.