Actin polymerization promoted by a heptapeptide, an analog of the actin-binding S site on myosin head.
Polymerization of G-actin to F-actin was indicated by an increase in light-scattering intensity after the addition of a heptapeptide (Ile-Arg-Ile-Cys(MT)-Arg-Lys-Gly-OEt), an analog of the actin-binding S-site on S-1 heavy chain. The half-maximal concentration of the heptapeptide which induced an increase in the light-scattering intensity at 25 degrees C was about 110 microM, which was in the range of the dissociation constant of this peptide with F-actin. The polymerization of G-actin to F-actin by binding of the heptapeptide was further demonstrated by ultracentrifugal separation, Pi liberation, and electron microscopy. The polymerization of G-actin was induced only by the heptapeptide, but not by fragments of the heptapeptide. The well known acceleration of polymerization of G-actin by the myosin head may be due to the binding of G-actin with the S-site on the myosin head.
Department of Chemistry, Faculty of Science, Hokkaido University, Japan.
M
M
Eto
F
F
Morita
N
N
Nishi
S
S
Tokura
T
T
Ito
K
K
Takahashi
D000199:Actins / Q000378:metabolism* / Q000648:ultrastructure; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004220:Disulfides / Q000737:chemistry; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009218:Myosins / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D011108:Polymers; D011817:Rabbits; D013379:Substrate Specificity
D000199:Actins; D004220:Disulfides; D009842:Oligopeptides; D010446:Peptide Fragments; D011108:Polymers; C053435:isoleucyl-arginyl-isoleucyl-cysteinyl-arginyl-lysyl-glycine ethyl ester; D009218:Myosins