Myosin light chain kinase steady-state kinetics: comparison of smooth muscle myosin II and nonmuscle myosin IIB as substrates.

ABSTRACT: Myosin light chain kinase (MLCK) phosphorylates S19 of the myosin regulatory light chain (RLC), which is required to activate myosin's ATPase activity and contraction. Smooth muscles are known to display plasticity in response to factors such as inflammation, developmental stage, or stress, which lead to differential expression of nonmuscle and smooth muscle isoforms. Here, we compare steady-state kinetics parameters for phosphorylation of different MLCK substrates: (1) nonmuscle RLC, (2) smooth muscle RLC, and heavy meromyosin subfragments of (3) nonmuscle myosin IIB, and (4) smooth muscle myosin II. We show that MLCK has a ~2-fold higher k_cat for both smooth muscle myosin II substrates compared with nonmuscle myosin IIB substrates, whereas K_m values were very simila

SUBMITTER: Alcala DB 

PROVIDER: S-EPMC5076371 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature