General Description
Actin, aortic smooth muscle (UniProt P62736; also known as Alpha-actin-2, Cell growth-inhibiting gene 46 protein) is encoded by the ACTA2 (also known as AAT6, ACTSA, ACTVS, GIG46, MYMY5) gene (Gene ID 59) in human. Actins are globular multi-functional proteins that serve as the basic building blocks of cytoskeletal microfilaments and are among the most conserved eukaryotic proteins. Six actin types exist, skeletal muscle alpha-actin is encoded by the ACTA1 gene, smooth muscle alpha-actin by the ACTA2 gene, cytoplasmic beta-actin by the ACTB gene, cardiac muscle alpha-actin by the ACTC1 gene, cytoplasmic gamma-actin by the ACTG1 gene, and smooth muscle gamma-actin by the ACTG2 (a.k.a. ACTA3) gene. Although actins show >90% overall sequence homology, isoforms do show spatial, temporal, and tissue-specific expresson patterns and only 50-60% homology is found in their 18 N-terminal residues. Cytoplasmic β and γ-actins, are thought to be present in all cells, while the other four actin isoforms are typically found in specific adult muscle tissue types. Actins exist in a variety of structural states, depending on the specific ionic conditions or the interaction with ligand proteins. The oligomeric and polymeric forms that actin molecules assume are dependent on the distinct conformations they adopt.
