Gammaactin

Gamma-actin is a cytoplasmic actin isoform in vertebrates. In humans, two gamma-actin genes exist: ACTG1, which encodes gamma-actin 1 and is expressed broadly in non-muscle cells, and ACTG2, which encodes gamma-actin 2 and is primarily expressed in smooth muscle tissues.

As a member of the actin family, gamma-actin polymerizes with globular actin to form filamentous F-actin, a major component of the cytoskeleton. It participates in cell shape maintenance, polarity, migration, cytokinesis, and vesicle transport by interacting with a range of actin-binding proteins.

The gamma-actin proteins are approximately 375 amino acids in length and show high sequence similarity to other actin isoforms, reflecting conserved core functions. Gamma-actin isoforms participate in various cytoskeletal structures, including stress fibers and cortical networks, with tissue-specific expression patterns influencing local dynamics.

Clinical relevance: Pathogenic variants in ACTG1 have been linked to Baraitser-Winter syndrome, a developmental disorder affecting brain structure, eyes, and facial features. Mutations in gamma-actin genes have also been associated with myopathies and other developmental conditions.

In research, gamma-actin is frequently used as a housekeeping gene for normalization in gene expression studies due to its widespread and relatively stable expression across tissues.