MYLK Protein, Human (Active, sf9, GST)

MYLK is a calcium/calmodulin-dependent myosin light chain kinase that regulates smooth muscle contraction by phosphorylating myosin light chains (MLC). It also modulates actin-myosin interaction through a non-kinase activity and phosphorylates PTK2B/PYK2 and myosin light chains. This protein plays roles in inflammatory responses (e.g., apoptosis, vascular permeability, leukocyte diapedesis), cell motility/morphology, airway hyperreactivity, and asthma-related processes. It is essential for tonic airway smooth muscle contraction underlying physiological and asthmatic airway resistance, as well as gastrointestinal motility. MYLK likely regulates endothelial/vascular permeability via cytoskeletal rearrangements. In the nervous system, it controls astrocytic process growth in culture and participates in synaptic transmitter release. As a critical mediator of fibroblast apoptosis signaling, MYLK also influences epithelial cell survival, particularly during wound healing by mediating actomyosin ring contraction. It induces RhoA-dependent membrane blebbing and activates TRPC5 channels via calcium-dependent plasma membrane localization, promoting cell (including tumor) migration and metastasis. Phosphorylation of PTK2B/PYK2 by MYLK activates ITGB2, enabling neutrophil transmigration in acute lung injury (ALI). MYLK may regulate optic nerve head astrocyte migration and mitotic cytoskeletal organization, while modulating tight junctions through ZO-1 exchange. In burn injuries, it mediates microvascular barrier dysfunction by phosphorylating MLC to induce endothelial contraction. It is crucial for intestinal barrier impairment and Giardia spp.-induced epithelial dysfunction via F-actin/ZO-1 reorganization. MYLK enables hypotonicity-induced Ca²⁺ entry and volume-sensitive organic osmolyte/anion channel (VSOAC) activation in cervical cancer cells and supports breast cancer cell proliferation via anti-apoptotic mechanisms.