Phosphorylation of dystrophin:effects on actin binding

Dystrophin is phosphorylated by several protein kinases. In this work, we have studied the effects of dystrophin phosphorylation on the binding to actin. Purified dystrophin was phosphorylated in vitro by the catalytic subunit of cAMP-dependent protein kinase (PKA), casein kinase II (CK-II), and protein kinase c (PKC). The results demonstrate that phosphorylation of dystrophin by PKA phosphorylation caused a three fold increase in dystrophin binding to actin. In contrast, phosphorylation by CK-II or PKC inhibited the binding to actin. These results indicate that phosphorylation of dystrophin modulates its interaction with the actin cytoskeleton. It is suggested that phosphorylation may be one mechanism for regulating protein turnover in muscle membrane-skeleton.