Both alpha-actinin 2 and 3 are key components of the muscle sarcomere; they are located at the Z line and bind to actin filaments as well as many other sarcomeric proteins. Alpha-actinin 2 is expressed in slow and fast skeletal muscle, as well as cardiac muscle and brain. ? The expression of alpha-actinin 3 however, is limited to fast muscle fibers. Recent studies show that alpha-actinin 3 provides an advantage for power and sprint activities.

We hypothesize that despite their high homology, alpha-actinin 2 and 3 might have different functions. To address this question, Behzad is generating knock-in mice that do not express alpha-actinin 2 and express alpha-actinin 3 under the control of alpha-actinin 2 promoter.