Purified anti-Myosin Light Chain Kinase Antibody, Myosin Light Chain Kinase, W18242A,BioLegend,648866

Myosin light chain kinase (MYLK) is a multifunctional serine/threonine-specific protein kinase that plays a pivotal role in regulating actomyosin contractility through the phosphorylation of myosin regulatory light chains (MLC). MYLK exists in multiple isoforms generated via alternative splicing, including the long isoform (smooth muscle MYLK), short isoform (non-muscle MYLK), and telokin, each with distinct tissue distribution and functional specificity. The canonical catalytic mechanism of MYLK involves Ca²⁺/calmodulin-dependent activation, which induces a conformational change in MYLK that facilitates ATP-dependent phosphorylation of MLC. This phosphorylation enhances actin-activated myosin ATPase activity, enabling cross-bridge cycling between myosin and actin filaments and thus driving cellular contraction, adhesion, and motility. In smooth muscle cells, MYLK activation is critical for contraction in vascular, respiratory, gastrointestinal, and genitourinary systems, acting downstream of G-protein–coupled receptor and receptor tyrosine kinase signaling. In endothelial cells, MYLK-mediated MLC phosphorylation increases actomyosin tension, modulating paracellular gap formation and vascular permeability in response to inflammatory mediators such as thrombin, histamine, and VEGF.  MYLK dysregulation contributes to diverse human diseases. In vascular disorders, overactivation of MYLK promotes hyperpermeability and tissue edema during sepsis, acute respiratory distress syndrome (ARDS), and ischemia-reperfusion injury. In the gastrointestinal tract, MYLK contributes to barrier defects in inflammatory bowel disease (IBD) by disrupting tight junctions, leading to increased intestinal permeability and exacerbating inflammation.