title: Gamma-Actinin, a new regulatory protein from rabbit skeletal muscle. II. Action on actin.
abstract: The interaction of gamma-actinin and actin was investigated under various conditions. It has been shown that gamma-actinin affects the G-F transformation of actin, causing an increase in the number of actin monomers required to form a nucleus in the initial step of polymerization. Sonicated fragments of F-actin and heavy meromyosin caused the immediate polymerization of actin under the influence of gamma-actinin. Therefore, it can be concluded that gamma-actinin inhibits the nucleation step of G-F transformation. Actin filaments which were formed in the presence of gamma-actinin (F-actin) were shown to possess certain characteristic properties when compared with control F-actin. These were as follows: F-actin solution had a high critical concentration; F-actin showed a high rate of depolymerization; the flow birefringence of F-actin decreased with time upon incubation in the absence of free ATP; finally, F-actin was demonstrated to have ATP-splitting activity. These dynamic features of F-actin were accounted for in terms of an increase in the rate constant of depolymerization in F-actin under the influence of gamma-actinin.
mesh_terms: D000185:Actinin / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D001718:Birefringence; D007700:Kinetics; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D009124:Muscle Proteins / Q000378:metabolism; D009132:Muscles / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D011817:Rabbits
chemical_list: D000199:Actins; D046911:Macromolecular Substances; D009124:Muscle Proteins; D000185:Actinin; D000251:Adenosine Triphosphatases