Human Actinin Alpha 3 (ACTN3) Protein

Background

ACTN3 encodes alpha-actinin-3, a protein primarily expressed in fast-twitch skeletal muscle fibers, where it contributes to muscle strength and power. Unlike its closely related isoform ACTN2, ACTN3 is specialized for rapid and forceful contractions, playing a structural role in maintaining sarcomeric integrity and optimizing muscle performance. A common polymorphism in the ACTN3 gene results in the absence of alpha-actinin-3 in a significant proportion of the population, which has been associated with variations in muscle performance. The "null" variant is linked to reduced muscle power but enhanced endurance, reflecting its evolutionary role in adapting to physical demands. ACTN3 is crucial in regulating the balance between muscle power and endurance, with implications in athletic performance, muscle health, and susceptibility to muscle-related disorders.