Phosphorylates a specific serine in the N-terminus of a myosin light chain, which leads to the formation of calmodulin/MLCK signal transduction complexes which allow selective transduction of calcium signals. ATP + L-seryl-[myosin light chain] = ADP + H(+) + O-phospho-L-seryl-[myosin light chain] ATP + L-threonyl-[myosin light chain] = ADP + H(+) + O-phospho-L-threonyl-[myosin light chain] Activated by phosphorylation on Tyr-478. Isoforms which lack this tyrosine residue are not regulated in this way. All catalytically active isoforms require binding to calcium and calmodulin for activation. All isoforms including Telokin bind calmodulin. Telokin is cytosolic and can translocate to the membrane upon stimulation. Isoform telokin is expressed in gizzard, heart, lung, intestine, and skeletal muscle although the levels of the expression in the latter were much less than that in the gizzard. The C-terminus is deglutamylated, leading to the formation of Myosin light chain kinase, smooth muscle, deglutamylated form. The C-terminus is variable, with one to five C-terminal glutamyl residues being removed producing five forms differring in their number of C-terminal glutamyl residues. Acetylated. Phosphorylation of telokin by PKG has no significant effect on its myosin binding activity, but promotes translocation to the membrane. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family.