MYL9

Myosin, a structural component of muscle, consists of two heavy chains and four light chains. The protein encoded by this gene is a myosin light chain that may regulate muscle contraction by modulating the ATPase activity of myosin heads. The encoded protein binds calcium and is activated by myosin light chain kinase. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq]

Full Name

myosin, light chain 9, regulatory

Function

Myosin regulatory subunit that plays an important role in regulation of both smooth muscle and nonmuscle cell contractile activity via its phosphorylation. Implicated in cytokinesis, receptor capping, and cell locomotion (PubMed:11942626, PubMed:2526655).

In myoblasts, may regulate PIEZO1-dependent cortical actomyosin assembly involved in myotube formation (By similarity).

Biological Process

Myofibril assembly Source: GO_Central
Platelet aggregation Source: UniProtKB
Regulation of muscle contraction Source: ProtInc

Cellular Location

Cytoskeleton
Other locations
cell cortex
Note: Colocalizes with F-actin, MYH9 and PIEZO1 at the actomyosin cortex in myoblasts.

Involvement in disease

Megacystis-microcolon-intestinal hypoperistalsis syndrome 4 (MMIHS4):
A form of megacystis-microcolon-intestinal hypoperistalsis syndrome, a congenital visceral myopathy primarily affecting females, and characterized by loss of smooth muscle contraction in the bladder and intestine. Affected individuals present at birth with functional obstruction of intestine, microcolon, dilation of bladder, and secondary hydronephrosis. The majority of cases have a fatal outcome due to malnutrition and sepsis, followed by multiorgan failure. MMIHS4 inheritance is autosomal recessive.

PTM

Phosphorylation increases the actin-activated myosin ATPase activity and thereby regulates the contractile activity. It is required to generate the driving force in the migration of the cells but not necessary for localization of myosin-2 at the leading edge. Phosphorylation is required for myotube formation.