Calcium regulation in chicken gizzard muscle and inosine triphosphate-induced superprecipitation of skeletal acto-gizzard myosin.
Inosine triphosphate (ITP) does not serve as a substrate for myosin light-chain kinase from gizzard muscle. That is to say, myosin light-chain is not phosphorylated in ITP media. Nevertheless, at pH 6.8, 1 mM or 5 mM ITP induces superprecipitation of skeletal acto-gizzard myosin. The ITP-induced superprecipitation occurs in the absence or presence of calcium ions, and regardless of whether gizzard myosin is phosphorylated or not. On the other hand, at pH 8, 5 MM ITP induces practically no superprecipitation of skeletal acto-gizzard unphosphorylated myosin, whereas it does induce a strong superprecipitation of skeletal acto-gizzard phosphorylated myosin. Superprecipitation is also independent of the presence or absence of calcium ions.
D000199:Actins / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002645:Chickens; D004533:Egtazic Acid / Q000494:pharmacology; D005895:Gizzard, Avian / Q000187:drug effects / Q000378:metabolism*; D007292:Inosine Nucleotides / Q000494:pharmacology*; D007293:Inosine Triphosphate / Q000494:pharmacology*; D007700:Kinetics; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation; D011817:Rabbits
D000199:Actins; D007292:Inosine Nucleotides; D007293:Inosine Triphosphate; D004533:Egtazic Acid; D009218:Myosins; D002118:Calcium