Fig. 4. SDS–PAGE showing parvalbumin expression in sheepshead red muscle from six body positions, ranging from 35–85% of the body length from the snout. The two isoforms occur in all body positions. In this animal, there is a gradual increase in the relative contribution of Parv1, from 50% Parv1 at 35% of body length to 67% Parv1 at 85% of body length. There is also a gradual decrease in total parvalbumin expression from anterior to posterior.