Shift of binding site at the interface between actin and myosin.
The molar ratio dependent change in the binding manner between actin and the lysine-rich sequence at the junction between 50K and 20K domains of subfragment 1 was studied by both protease digestion and cross-linking with 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide. The tryptic cleavage site at the function between 50K and 20K was found to be located between the third and fourth lysine residues in the lysine-rich sequence -KKGGKKK-. This site was not protected by actin when the molar ratio of actin to subfragment 1 was 1:1 but was protected at 2:1 and 3:1. The V8 protease cleavage site of chicken subfragment 1 and the elastase cleavage site of rabbit subfragment 1 were found to be located four residues away from the N-terminus of the lysine-rich sequence. Unlike the tryptic cleavage site, this site was protected by actin more when the molar ratio of actin to subfragment 1 was 1:1 than when it was 2:1 and 3:1. To understand the reason for the opposite effect of the molar ratio observed at the middle of and at four residues away from the lysine-rich sequence, actual cross-linked residue(s) was (were) determined by subjecting cross-linked product to a protein sequencer. It was found that the cross-linked sites were mainly at the first and second lysine residues of the lysine-rich sequence when the molar ratio of actin to subfragment 1 was 1:1.(ABSTRACT TRUNCATED AT 250 WORDS)
Yamamoto
K
K
Faculty of Liberal Arts, University of the Air, Chiba, Japan.
D000199:Actins / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D009218:Myosins / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism; D011817:Rabbits
D000199:Actins; D010447:Peptide Hydrolases; D009218:Myosins; D008239:Lysine