Bisphosphorylation of cardiac troponin I modulates the Ca2+‐dependent binding of myosin subfragment S1 to reconstituted thin filaments

FEBS Letters

Heilmeyer, Ludwig M.G.²  Jaquet, Kornelia¹  Geeves, Michael A.³  Reiffert, Silke U.²  Ritchie, Marcia D.³ 

[1] Herz-und Diabeteszentrum Nordrhein-Westfalen, Georgstraβe 11, 32545 Bad Oeynhausen, Germany;Ruhr-Universität Bochum, Institut für Physiologische Chemie, Abteilung für Biochemie Supramolekularer Systeme, 44780 Bochum, Germany;Max-Planck-Institut für molekulare Physiologie, Abteilung Physikalische Biochemie, Rheinlanddamm 201, 44139 Dortmund, Germany

关键词: Cardiac troponin;    Phosphorylation;    Calcium regulation;    Thin filament;    Myosin S1 binding;   

DOI  :  10.1016/0014-5793(96)00274-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have reconstituted thin filaments comprising pyrene-labelled actin (pyr-actin), tropomyosin (Tm) and cardiac troponin (cTn). cTn was isolated in two defined phosphorylation states; completely dephosphorylated on all subunits and with only the cTnI subunit bisphosphorylated. The thin filament was saturated with cTn at a pyr-actin/Tm/cTn ratio of 7:1:1. The calcium-dependent binding of S1 to thin filaments was measured in a stopped-flow spectrophotometer and the dependence of the observed rate constant on [Ca²⁺] fitted to the Hill equation. The only significant difference between the two phosphorylation states of the filaments was a 0.36 decrease in the pCa₅₀ on bisphosphorylation.

【 授权许可】

Unknown