Actinin Alpha 3 (ACTN3)

Actinin, alpha 3, also known as ACTN3, is a protein which in humans is encoded by the ACTN3 gene.Alpha-actinin is an actin-binding protein with multiple roles in different cell types. This gene expression is limited to skeletal muscle. It is localized to the Z-disc and analogous dense bodies, where it helps to anchor the myofibrillar actin filaments.

Skeletal muscle is composed of long cylindrical cells called muscle fibers. There are two types of muscle fibers, slow twitch or muscle contraction (type I) and fast twitch (type II). Slow twitch fibers are more efficient in using oxygen to generate energy whilst fast twitch fibers are less efficient. However, fast twitch fibers fire more rapidly and generate more force.