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). (updated: Nov. 7, 2018)
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
No sequence conservation computed yet.
This protein is annotated as membranous in Gene Ontology.
Total structural coverage: 100%
No model available.
(right-click above to access to more options from the contextual menu)
The reference OMIM entry for this protein is 102630
Actin, beta; actb
Beta-actin
Actin, cytoplasmic, 1
CLONING
From studies of the amino acid sequence of cytoplasmic and muscle actins, Vandekerckhove and Weber (1978) concluded that mammalian cytoplasmic actins are the products of 2 different genes and differ by many amino acids from muscle actin. In a neoplastic cell line resulting from treatment of cultured human diploid fibroblasts with a chemical mutagen, Leavitt et al. (1982) observed a mutant form of beta actin. Toyama and Toyama (1984) isolated and characterized lines of KB cells resistant to cytochalasin B. They found that one resistant line had an alteration in beta-actin. Such cells bound less cytochalasin B than did parental KB cells. The authors suggested that the primary site of action of cytochalasin B on cell motility processes is beta-actin. Using chick beta-actin cDNA as probe, Gunning et al. (1983) cloned beta-actin and gamma-actin (ACTG1;
102560) from a fibroblast cDNA library. They noted that the N-terminal methionine is posttranslationally removed from the mature beta- and gamma-actin proteins.
MAPPING
Ng et al. (1985) assigned the ACTB gene to 7pter-q22 by Southern blot analysis of DNA from somatic cell hybrids. Habets et al. (1992) generated hybrids that harbor only specific regions of human chromosome 7 and assigned the ACTB locus to 7p15-p12. Ueyama et al. (1996) used fluorescence in situ hybridization to map ACTB to 7p22. By PCR of somatic cell hybrid DNAs, they mapped 4 ACTB pseudogenes to other chromosomes.
GENE FUNCTION
Interaction of phospholipase D (see PLD1;
602382) with actin microfilaments regulates cell proliferation, vesicle trafficking, and secretion. Kusner et al. (2002) found that highly purified globular actin (G-actin) inhibited both basal and stimulated PLD1 activity, whereas filamentous actin (F-actin) had the opposite effect. Actin-induced modulation of PLD1 activity was independent of the activating stimulus. The effects of actin on PLD1 were isoform specific: human platelet actin, which exists in a 5:1 ratio of beta- and gamma-actin, was only 45% as potent and 40% as efficacious as rabbit skeletal muscle alpha-actin. Localization of beta-actin mRNA to sites of active actin polymerization modulates cell migration during embryogenesis, differentiation, and possibly carcinogenesis. This localization requires the oncofetal protein ZBP1 (
608288), which binds to a conserved 54-nucleotide element in the 3-prime untranslated region of the beta-actin mRNA known as the 'zipcode.' ZBP1 promotes translocation of the beta-actin transcript to actin-rich protrusions in primary fibroblasts and neurons. Huttelmaier et al. (2005) showed that chicken ZBP1 modulates the translation of beta-actin mRNA. ZBP1 associates with the beta-actin transcript in the nucleus and prevents premature translation in the cytoplasm by blocking translation initiation. Translation occurs only when the ZBP1-RNA complex reaches its destination at the periphery of the cell. At the endpoint of mRNA transport, the protein kinase Src (
190090) promotes translation by phosphorylating a key tyrosine residue in ZBP1 that is required for binding to RNA. These sequential events provide both temporal and spatial control over beta-actin mRNA translation, which is important for cell migration and neurite outgrowth. In immunoprecipitation studies of embryonic fibroblasts from wildtype and knockout mice deficient in the arginylation enzyme Ate1 (
607103), Karakozova et al. (2006) found that approximately 40% of intrace ...
More on the omim web site
Subscribe to this protein entry history
Nov. 16, 2018: Protein entry updated
Automatic update: Entry updated from uniprot information.
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
March 15, 2016: Protein entry updated
Automatic update: OMIM entry 102630 was added.