title: Peptide fragments of the heavy-chain region of phosphorylated and dinitrophenylated gizzard myosin.
abstract: Sulfopropyl (SP) Sephadex chromatography of trypsin-pepsin digests of dinitrophenylated gizzard myosin, pretreated with and without the myosin light-chain kinase calcium-calmodulin phosphorylating system, yielded similar elution patterns and nine peptide fractions were found. From a comparison with trypsin-pepsin digests of the heavy chains of dinitrophenylated myosin, pretreated with and without the phosphorylating system, it was established that peptide I, a major peptide fraction, was part of the 17-kDa dinitrophenylated light chain. Phosphorylation of myosin did not change the dinitrophenyl group content of peptide I but it did result in a significant increase in the dinitrophenylation of other peptides. The peptides contained only S-dinitrophenyl cysteine. Peptide III, previously considered to be part of the light-chain region (Bailin, G. and Lopez, F. (1982) J. Biol. Chem. 257, 264-270), was shown to originate in the heavy chains of myosin based on a comparison of the elution patterns of the digests of modified myosin and its heavy chains. Several neutral and basic peptides (peptides III to IX) originated in the heavy-chain region and they were different from those from the heavy chains of rabbit skeletal myosin. Phosphorylation of the 20-kDa light chain shifted the dinitrophenylation of the sulfhydryl groups from the 17-kDa light chain to the heavy chains of myosin, predominantly. These thiol groups do not resemble the fast-reacting -SH groups of rabbit skeletal myosin. The light chains are involved, in part, in making sites available on myosin that are necessary for actin-myosin interaction.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002645:Chickens; D004139:Dinitrofluorobenzene / Q000378:metabolism; D005895:Gizzard, Avian / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D010766:Phosphorylation; D011485:Protein Binding; D014316:Tritium
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D014316:Tritium; D000255:Adenosine Triphosphate; D004139:Dinitrofluorobenzene; D009218:Myosins