Calcium binding and calcium-sensitivity of heavy meromyosin and subfragment-1 from squid (Todarodes pacificus) mantle and scallop (Patinopecten yessoensis) adductor muscles.
1. HMM and S-1 both bind one mol of calcium per mole of head, and a half of the calcium binding was diminished upon magnesium addition (10 mM) at the low affinity site. 2. The Mg-ATPase activity of HMM (without actin) was fully activated by the binding of one mol of calcium bound per mol of HMM. 3. The calcium binding profile to S-1 is the same as that to HMM, however, the Mg-ATPase activity of S-1 is independent of calcium binding. It is suggested that there are two kinds of myosin head (or S-1) in molluscan myosin, functionally different in calcium binding properties.
Kamiya
S
S
Department of Food Science, Faculty of Fisheries, Hokkaido University, Japan.
Konno
K
K
D000818:Animals; D001665:Binding Sites; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D049832:Decapodiformes / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008974:Mollusca / Q000378:metabolism*; D015879:Myosin Subfragments / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism*
D015879:Myosin Subfragments; D010446:Peptide Fragments; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins; D008274:Magnesium; D002118:Calcium