title: On the mechanism for inactivation of cytochalasin binding activity associated with F-actin and spectrin-band 4.1-actin complex by sulfhydryl reagents.
abstract: The sulfhydryl group modifying reagent, p-hydroxymercuribenzoate, inhibited the cytochalasin binding activity of the actin nuclei in the spectrin-band 4.1-actin complex from the erythrocyte membrane and of muscle F-actin. Kinetic studies indicated that while the cytochalasin binding activity was immediately inhibited, the actin remained filamentous and depolymerized slowly over a period of 1 to 2 h. Scatchard analysis of the binding data revealed that initially only the KD was affected. However, prolonged incubation led to depolymerization of the F-actin and dissociation of the spectrin-band 4.1-actin complex, resulting in loss of binding sites. It thus appears that certain actin sulfhydryl group(s) are important for cytochalasin binding. However, the most reactive sulfhydryl group (cys-374) on actin does not appear to be involved.
mesh_terms: D000199:Actins / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism*; D002729:Chloromercuribenzoates / Q000494:pharmacology; D003571:Cytochalasin B / Q000097:blood / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D004910:Erythrocyte Membrane / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008565:Membrane Proteins; D009132:Muscles / Q000378:metabolism; D009479:Neuropeptides; D011485:Protein Binding / Q000187:drug effects; D013049:Spectrin / Q000378:metabolism*; D013439:Sulfhydryl Reagents / Q000494:pharmacology*; D020245:p-Chloromercuribenzoic Acid
chemical_list: D000199:Actins; D001798:Blood Proteins; D002729:Chloromercuribenzoates; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D009479:Neuropeptides; D013439:Sulfhydryl Reagents; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D013049:Spectrin; D003571:Cytochalasin B; D020245:p-Chloromercuribenzoic Acid; D005033:Ethylmaleimide