Myosin light chain phosphatase catalytic subunit dephosphorylates cardiac myosin via mechanisms dependent and independent of the MYPT regulatory subunits.

ABSTRACT: Cardiac muscle myosin regulatory light chain (RLC) is constitutively phosphorylated at ∼0.4 mol phosphate/mol RLC in normal hearts, and phosphorylation is maintained by balanced activities of dedicated cardiac muscle-specific myosin light chain kinase and myosin light chain phosphatase (MLCP). Previously, the identity of the cardiac-MLCP was biochemically shown to be similar to the smooth muscle MLCP, which is a well-characterized trimeric protein comprising the regulatory subunit (MYPT1), catalytic subunit PP1cβ, and accessory subunit M20. In smooth muscles in vivo, MYPT1 and PP1cβ co-stabilize each other and are both necessary for normal smooth muscle contractions. In the cardiac muscle, MYPT1 and MYPT2 are both expressed, but contributions to physiological regulation of cardiac myosin d

SUBMITTER: Lee E 

PROVIDER: S-EPMC9418503 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature