PICK1 - A PERINUCLEAR BINDING-PROTEIN AND SUBSTRATE FOR PROTEIN-KINASE-C ISOLATED BY THE YEAST 2-HYBRID SYSTEM

Protein kinase C (PKC) plays a central role in the control of prolifer ation and differentiation of a wide range of cell types by mediating t he signal transduction response to hormones and growth factors. Upon a ctivation by diacylglycerol, PKC translocates to different subcellular sites where it phosphorylates numerous proteins, most of which are un identified. We used the yeast two-hybrid system to identify proteins t hat interact with activated PKC alpha. Using the catalytic region of P KC fused to the DNA binding domain of yeast GAL4 as ''bait'' to screen a mouse T cell cDNA library in which cDNA was fused to the GAIA activ ation domain, we cloned several novel proteins that interact with C-ki nase (PICKs). One of these proteins, designated PICK1, interacts speci fically with the catalytic domain of PKC and is an efficient substrate for phosphorylation by PKC in vitro and in vivo. PICK1 is localized t o the perinuclear region and is phosphorylated in response to PKC acti vation. PICK1 and other PICKs may play important roles in mediating th e actions of PKC.