In vitro phosphorylation of tropomyosin by a kinase from chicken embryo.
A tropomyosin kinase has been partially purified from the leg muscle of 11-day-old chick embryos by ammonium sulfate precipitation and DEAE and phosphocellulose chromatography. The tropomyosin kinase requires Mg2+ for its activity, but Ca2+ and cyclic AMP are not needed. Increase in KC1 concentration decreased the tropomyosin kinase activity with over 90% inhibition at 0.2 M KC1. The alpha-tropomyosin subunit from rabbit and chicken skeletal muscle was phosphorylated about five times faster than the beta-tropomyosin subunit. Smooth muscle tropomyosin from chicken gizzard was not phosphorylated. The in vitro phosphorylation site in rabbit and chicken skeletal tropomyosins is a single serine residue close to the COOH terminus, a region intimately engaged in the head to tail polymerization of tropomyosin. Since the amino acid sequences of rabbit alpha- and beta-tropomyosin and chicken alpha-tropomyosin in this region are known, their phosphorylation sites can be unambiguously assigned as the penultimate residue, serine 283.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002642:Chick Embryo; D002645:Chickens; D000242:Cyclic AMP / Q000494:pharmacology; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008970:Molecular Weight; D009132:Muscles / Q000201:enzymology*; D010766:Phosphorylation; D011189:Potassium Chloride / Q000494:pharmacology; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D014335:Tropomyosin / Q000302:isolation & purification / Q000378:metabolism*
D014335:Tropomyosin; D011189:Potassium Chloride; D000242:Cyclic AMP; D011494:Protein Kinases; C041311:tropomyosin kinase; D008274:Magnesium; D002118:Calcium