ACTA1

The product encoded by this gene belongs to the actin family of proteins, which are highly conserved proteins that play a role in cell motility, structure and integrity. Alpha, beta and gamma actin isoforms have been identified, with alpha actins being a major constituent of the contractile apparatus, while beta and gamma actins are involved in the regulation of cell motility. This actin is an alpha actin that is found in skeletal muscle. Mutations in this gene cause a variety of myopathies, including nemaline myopathy, congenital myopathy with excess of thin myofilaments, congenital myopathy with cores, and congenital myopathy with fiber-type disproportion, diseases that lead to muscle fiber defects with manifestations such as hypotonia.

Actin, Alpha 1, Skeletal Muscle

Actin, Alpha 1, Skeletal Muscle; Nemaline Myopathy Type 3; ACTA; Actin, Alpha Skeletal Muscle; Alpha-Actin-1; CFTD1; CFTDM; ASMA;

Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells.

Cellular response to organonitrogen compound
Mesenchyme migration
Muscle contraction
Muscle filament sliding
Positive regulation of gene expression
Response to extracellular stimulus
Response to lithium ion
Response to mechanical stimulus
Response to steroid hormone
Skeletal muscle fiber adaptation
Skeletal muscle fiber development
Skeletal muscle thin filament assembly

Cytoskeleton

Nemaline myopathy 3 (NEM3): A form of nemaline myopathy. Nemaline myopathies are muscular disorders characterized by muscle weakness of varying severity and onset, and abnormal thread-like or rod-shaped structures in muscle fibers on histologic examination.
Myopathy, actin, congenital, with excess of thin myofilaments (MPCETM): A congenital muscular disorder characterized at histological level by areas of sarcoplasm devoid of normal myofibrils and mitochondria, and replaced with dense masses of thin filaments. Central cores, rods, ragged red fibers, and necrosis are absent.
Myopathy, congenital, with fiber-type disproportion (CFTD): A genetically heterogeneous disorder in which there is relative hypotrophy of type 1 muscle fibers compared to type 2 fibers on skeletal muscle biopsy. However, these findings are not specific and can be found in many different myopathic and neuropathic conditions.
Myopathy, scapulohumeroperoneal (SHPM): An autosomal dominant muscular disorder characterized by progressive muscle weakness with initial scapulo-humeral-peroneal and distal distribution. Over time, muscle weakness progresses to proximal muscle groups. Clinical characteristics include scapular winging, mild lower facial weakness, foot drop due to foot eversion and dorsiflexion weakness, and selective muscle atrophy. Age at onset and disease progression are variable.

Oxidation of Met-46 and Met-49 by MICALs (MICAL1, MICAL2 or MICAL3) to form methionine sulfoxide promotes actin filament depolymerization. MICAL1 and MICAL2 produce the (R)-S-oxide form. The (R)-S-oxide form is reverted by MSRB1 and MSRB2, which promotes actin repolymerization.
Monomethylation at Lys-86 (K84me1) regulates actin-myosin interaction and actomyosin-dependent processes. Demethylation by ALKBH4 is required for maintaining actomyosin dynamics supporting normal cleavage furrow ingression during cytokinesis and cell migration.
Methylated at His-75 by SETD3.
(Microbial infection) Monomeric actin is cross-linked by V.cholerae toxins RtxA and VgrG1 in case of infection: bacterial toxins mediate the cross-link between Lys-52 of one monomer and Glu-272 of another actin monomer, resulting in formation of highly toxic actin oligomers that cause cell rounding. The toxin can be highly efficient at very low concentrations by acting on formin homology family proteins: toxic actin oligomers bind with high affinity to formins and adversely affect both nucleation and elongation abilities of formins, causing their potent inhibition in both profilin-dependent and independent manners.