Isolation and characterization of profilactin and profilin from calf thymus and brain.

1. Profilactin and profilin have been purified from calf thymus and calf brain. Thymus profilactin could be crystallized with a similar technique as described earlier for the spleen protein. 2. Preparations of profilactin from the three calf tissues spleen, thymus and brain contain a mixture of beta actin and gamma actin. The ratio beta/gamma differs between the tissues, but is constant throughout the purification steps. 3. The properties of profilin isolated from three sources (spleen, thymus and brain) indicate that it is a highly conserved protein.