Direct binding of myosin II to phospholipid vesicles via tail regions and phosphorylation of the heavy chains by protein kinase C.

摘要: Abstract Recent cloning and sequencing studies suggest that heavy chains of all non-muscle myosins II have a protein kinase C (PKC) phosphorylation site within their tail regions. A fragment human macrophage myosin chain, encompassing its COOH-terminal 396 amino acids (MIIAF46), was expressed in Escherichia coli to provide model system for study PKC-mediated phosphorylation. PKC phosphorylated this when phosphatidylserine (PS) liposomes were present, but not made from PS/phosphatidylcholine (PC) used. The reaction required Ca2+, other activators such as diacylglycerol (DG) or phosphatidylinositol 4,5-bisphosphate. Phosphorylation MIIAF46 observed the presence micelles PS PS/DG. Similar results obtained using native purified bovine brain chicken intestine brush border. light chains, contrast, occurred even with PS/PC if DG present. Addition PS/DG significantly increased turbidities at 340 nm II, extent increase depended upon type Also, shifted gel filtration elution positions II. In PS/PC/DG gave only slight turbidity fragments did noticeably shift positions. These bind via regions affinities specific each isoform, binding is dependent composition, phosphorylates PS-bound chains.