Unfair competition governs the interaction of pCPI-17 with myosin phosphatase (PP1-MYPT1)

eLife

David Shalloway¹  Joshua J Filter¹  Byron C Williams¹  Michael L Goldberg¹  Masumi Eto² 

[1] Department of Molecular Biology and Genetics, Cornell University, Ithaca, United States;Department of Molecular Physiology and Biophysics, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, United States;

关键词: smooth muscle contraction/relaxation;    myosin phosphatase;    CPI-17;    unfair competition;   

DOI  :  10.7554/eLife.24665

来源: DOAJ

【 摘 要 】

The small phosphoprotein pCPI-17 inhibits myosin light-chain phosphatase (MLCP). Current models postulate that during muscle relaxation, phosphatases other than MLCP dephosphorylate and inactivate pCPI-17 to restore MLCP activity. We show here that such hypotheses are insufficient to account for the observed rapidity of pCPI-17 inactivation in mammalian smooth muscles. Instead, MLCP itself is the critical enzyme for pCPI-17 dephosphorylation. We call the mutual sequestration mechanism through which pCPI-17 and MLCP interact inhibition by unfair competition: MLCP protects pCPI-17 from other phosphatases, while pCPI-17 blocks other substrates from MLCP’s active site. MLCP dephosphorylates pCPI-17 at a slow rate that is, nonetheless, both sufficient and necessary to explain the speed of pCPI-17 dephosphorylation and the consequent MLCP activation during muscle relaxation.

【 授权许可】

Unknown