The identification of actin as a major lymphocyte component.

Lymphocytes derived from pig mesenteric lymph node and mouse spleen have been shown to contain a major protein conponent which a) co-migrates on one-dimensional (SDS-PAGE with purified pig muscle actin, and b) possesses the same isoelectric point as muscle actin on two-dimensional gel electrophoresis. Further, limited proteolytic digestion of the lymphocyte actin-comigrating band by S. aureus V8-protease revealed extensive primary sequence hemology with purified muscle actin. Based on the virtual identity of molecular size charge, and primary sequence, we conclude that the actin-comigrating band represents lymphocyte actin. The appearance of lymphocyte actin as a nonspecific "contaminant" of immune precipitates has also been discussed.