Actin is a highly conserved protein involved in cell motility, structure, and integrity. Six functional actin isoforms exist and were named based on their electrophoretic mobility and distribution including alpha-cardiac muscle actin (aCAA), alpha-skeletal muscle actin (aSKA), alpha-smooth muscle actin (aSMA), beta-cytoplasmic actin (bCYA), gamma-cytoplasmic actin (gCYA) and gamma-smooth muscle actin (gSMA) (1). The cytoplasmic isoforms, beta-actin and gamma-actin, are nearly identical, differing by only 4 amino acids at the N-terminus with a theoretical molecular weight of 42 kDa (2). Beta-actin is ubiquitously expressed in eukaryotic cells and considered a housekeeping gene which is frequently used as a loading control for assays involving protein detection, such as Western blotting (3,4).
1. Vandekerckhove J, Weber K. 1978. At least six different actins are expressed in a higher mammal: an analysis based on the amino acid sequence of the amino-terminal tryptic peptide. J Mol Biol. 126(4):783-802. PMID: 745245
2. Gimona M, Vandekerckhove J, Goethals M, Herzog M, Lando Z, Small JV. (1994) Beta-actin specific monoclonal antibody. Cell Motil Cytoskeleton. 27(2):108-16. PMID: 8162619
3. Holden VI, Lenio S, Kuick R, Ramakrishnan SK, Shah YM, Bachman MA. (2014) Bacterial siderophores that evade or overwhelm Lipocalin 2 induce HIF-1a and pro-inflammatory cytokine secretion in cultured respiratory epithelial cells Infect Immun. 82(9):3826-36 PMID: 24980968
4. Tsai WL, Yeh PH, Tsai CY, Ting CT, Chiu YH, Tao MH, Li WC, Hung SC. (2016) Efficient Programming of Human Mesenchymal Stem Cell Derived Hepatocytes by Epigenetic Regulations. J. Gastroenterol. Hepatol. 32(1):261-269. PMID: 27218433