Conformational changes in subdomain‐2 of G‐actin upon polymerization into F‐actin and upon binding myosin subfragment‐1

[摘要]

The susceptibility of subdomain-2 of actin to different proteases has been examined, for G-actin, F-actin, G-actin-S₁(A₂) and F-actin-S₁(A₂) complexes on a comparative basis. The sites of subtilisin, α-chymotrypsin and trypsin attack, exposed on G-actin, are protected in F-actin, F-actin-S₁(A₂) as well as in the G-actin-S₁(A₂) complex. In contrast, a new cleavage site (Arg³⁹-His⁴⁰) for ArgC protease, which is protected in G-actin, is exposed in G-actin-S₁(A₂) as well as in F-actin and F-actin-S₁(A₂). These results are consistent with the previously proposed structural analogy between the ternary (G-actin)₂S₁ and the F-actin-S₁ complexes, and provide information on the mechanism of S₁-induced polymerization of G-actin.

[学科分类] 生物化学/生物物理

[关键词] Actin;Myosin;Actomysin interaction;Conformational change;Limited proteolysis