COORDINATION OF 3 SIGNALING ENZYMES BY AKAP79, A MAMMALIAN SCAFFOLD PROTEIN

Multivalent binding proteins, such as the yeast scaffold protein Steri le-5, coordinate the location of kinases by serving as platforms for t he assembly of signaling units. Similarly, in mammalian cells the cycl ic adenosine 3',5'-monophosphate-dependent protein kinase (PKA) and ph osphatase 2B [calcineurin (CaN)] are complexed by an A kinase anchorin g protein, AKAP79. Deletion analysis and binding studies demonstrate t hat a third enzyme, protein kinase C (PKC), binds AKAP79 at a site dis tinct from those bound by PKA or CaN. The subcellular distributions of PKC and AKAP79 were similar in neurons. Thus, AKAP79 appears to funct ion as a scaffold protein for three multifunctional enzymes.