Beta-actin

Function

Actin is a highly conserved protein that polymerizes to produce filaments that form cross-linked networks in the cytoplasm of cells (PubMed:29581253). Actin exists in both monomeric (G-actin) and polymeric (F-actin) forms, both forms playing key functions, such as cell motility and contraction (PubMed:29581253). In addition to their role in the cytoplasmic cytoskeleton, G- and F-actin also localize in the nucleus, and regulate gene transcription and motility and repair of damaged DNA (PubMed:29925947).

Involvement in disease

Dystonia, juvenile-onset

DJO

A form of dystonia with juvenile onset. Dystonia is defined by the presence of sustained involuntary muscle contraction, often leading to abnormal postures. Patients with juvenile-onset dystonia manifest progressive, generalized, dopa-unresponsive dystonia, developmental malformations and sensory hearing loss.

None

The disease is caused by variants affecting the gene represented in this entry.

Baraitser-Winter syndrome 1

BRWS1

A rare developmental disorder characterized by the combination of congenital ptosis, high-arched eyebrows, hypertelorism, ocular colobomata, and a brain malformation consisting of anterior-predominant lissencephaly. Other typical features include postnatal short stature and microcephaly, intellectual disability, seizures, and hearing loss.

None

The disease is caused by variants affecting the gene represented in this entry.

Post-translational modifications

ISGylated.

Oxidation of Met-44 and Met-47 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 promote actin repolymerization.

Monomethylation at Lys-84 (K84me1) regulates actin-myosin interaction and actomyosin-dependent processes (PubMed:23673617). Demethylation by ALKBH4 is required for maintaining actomyosin dynamics supporting normal cleavage furrow ingression during cytokinesis and cell migration (PubMed:23673617).

Methylated at His-73 by SETD3 (PubMed:30526847, PubMed:30626964, PubMed:30785395, PubMed:31388018). Methylation at His-73 is required for smooth muscle contraction of the laboring uterus during delivery (By similarity).

Actin, cytoplasmic 1, N-terminally processed

N-terminal acetylation by NAA80 affects actin filament depolymerization and elongation, including elongation driven by formins (PubMed:29581253). In contrast, filament nucleation by the Arp2/3 complex is not affected (PubMed:29581253).

(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-50 of one monomer and Glu-270 of another actin monomer, resulting in formation of highly toxic actin oligomers that cause cell rounding (PubMed:19015515). 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 (PubMed:26228148).

Sequence similarities

Belongs to the actin family.

Cellular localization

• Cytoplasm
• Cytoskeleton
• Nucleus
• Localized in cytoplasmic mRNP granules containing untranslated mRNAs.

Alternative names

• Beta-actin
• ACTB

Database links

• entrezGene:60
• omim:102630
• swissprot:P60709

Target type

Proteins

Molecular weight

41737Da