Insights into the Structural and Functional Properties of Actin Isoforms in Different Model Organisms

Actin proteins are highly conserved cytoskeletal elements that play crucial roles in numerous cellular processes in eukaryotes, including muscle contraction, maintenance of cell shape, motility, and division. They facilitate essential functions such as cytokinesis, surface translocation, vesicle fusion, and environmental sensing. The three primary isoforms-Alpha, Beta, and Gamma exhibit distinct localization and functional profiles, highlighting their specialized roles in both muscle and non-muscle cells. Alpha-actins are predominantly present in skeletal, cardiac, and smooth muscle tissues, contributing to contraction and mechanical support, while Beta-actin is essential for cellular motility and lamella formation. Gamma-actin primarily provides structural stability in dynamic tissues like the inner ear and intestines. Although the overall sequence and structure of actin are highly conserved, subtle amino acid variations, such as DEDE, DDEE and EEED in Alpha actin, DDD in Beta cytoplasmic actin and EEE in Gamma actin, give rise to specific biological functions. The review also addresses the significance of single nucleotide polymorphisms (SNPs) within actin genes, revealing how genetic variability impacts actin function and contributes to disease susceptibility, including cardiomyopathies, muscular dystrophies and some immune or neurological disorders. Additionally, environmental factors, such as diet and micronutrient intake, can modulate actin expression through gene-environment interactions. This review offers insights into the structural diversity and regulatory mechanisms of actin isoforms, enhancing our understanding of their vital roles in cellular dynamics and their implications for health and disease.