alpha-actinin-3

ACTN3

A gene on chromosome 11q13-q14 that encodes an actin-binding bundling protein expressed only in skeletal muscle, which localises to the Z-disc and analogous dense bodies, where it helps to anchor the myofibrillar actin filaments.

alpha-actinin-3

ACTN3, a group of genes one of which, the R allele, codes for the fast-acting muscle protein actinin. The X allele does not produce this protein. Interestingly, 95 percent of champion sprinters have at least one copy of the R allele and 50 percent have two. In controls, 72 percent have one R allele and only 30 percent have two.