title: [Modulation of S-1 conformation and inhibition of the skeletal muscle S-1-ATPase by calponin of the mussel].
abstract: A novel 40 kDa protein has been detected in native thin filaments from catch muscles of the mussel Crenomytilus grayanus. In this study, using skeletal muscle actin and S-1, we investigated the effects of the mussel 40-kDa actin-binding protein on the acto · S-1 ATPase activity. On increasing the 40-kDa actin-binding protein (CaP-40) concentration, the actin-activated ATPase activity decreased, and was inhibited 80% at a CaP-40 to actin ratio of 0.5. Polarized fluorimetry technique and glycerinated muscle fibers were used to study effects of CaP-40 on the orientation and mobility of fluorescent label 1.5-IAEDANS specifically bound to CyS-707 of myosin subfragment-1 in the absence of nucleotide, and in the presence of MgADP or MgATP. We have concluded that CaP-40 binding to actin affects the strong binding of myosin to actin but has no effect on the weak binding. Thus, the influence of the CaP-40 on the formation of strong actomyosin binding forms A · M and A · M · ADP manifests itself by a decrease in the relative content of myosin cross-bridges strongly bound with actin, which probably results in a decrease in the relative content of "switch on" actin monomers in thin filaments. This suggests that, as calponin CaP-40 selects its target the phase of strong actomyosin binding binding which preceded by a phase generating power stroke.
authors.forename: V V
authors.initials: VV
authors.lastname: Sirenko
authors.forename: A O
authors.initials: AO
authors.lastname: Simonian
authors.forename: A V
authors.initials: AV
authors.lastname: Dobrzhanskaia
authors.forename: N S
authors.initials: NS
authors.lastname: Shelud'ko
authors.forename: Iu S
authors.initials: IuS
authors.lastname: Borovikov
mesh_terms: D000199:Actins / Q000737:chemistry / Q000378:metabolism; D000205:Actomyosin / Q000737:chemistry / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D049872:Bivalvia / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D005456:Fluorescent Dyes; D008840:Microfilament Proteins / Q000737:chemistry* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology*; D015879:Myosin Subfragments / Q000737:chemistry* / Q000378:metabolism; D009282:Naphthalenesulfonates; D011485:Protein Binding; D011487:Protein Conformation; D000096985:Calponins
chemical_list: D000199:Actins; D000205:Actomyosin; D000255:Adenosine Triphosphate; D002135:Calcium-Binding Proteins; D005456:Fluorescent Dyes; D008840:Microfilament Proteins; D015879:Myosin Subfragments; D009282:Naphthalenesulfonates; D000096985:Calponins; C032162:AEDANS-calmodulin