Kinetic Scheme of Myosin Phosphorylation by ZIP Kinase.

ABSTRACT: Zipper-interacting protein kinase (ZIPK) is a ubiquitous serine/threonine protein kinase that plays pivotal roles in regulating cell motility, division, and smooth muscle contractility through phosphorylation of myosin. In this study, we systematically investigated the phosphorylation reactions of smooth muscle myosin (SMM) by ZIPK. We found that ZIPK phosphorylates MRLC sequentially, first at Ser¹⁹ and then at Thr¹⁸, determined by quantitative mass spectrometry analysis on wild-type MRLC. Analysis on phosphomimic and unphosphorylatable MRLC mutants indicates that the phosphorylation rate at Ser¹⁹ on unphosphorylated MRLC is 1.5 times faster than that at Thr¹⁸ on Ser¹⁹-phosphorylated MRLC. Comparison between SMM and isolated MRLC revea

SUBMITTER: Yamaguchi M 

PROVIDER: S-EPMC12713720 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature