Plasma membranes purified from myeloid leukemia cells before and after differentiation. I. Characterization of spectrin-like proteins and increased association of actin.
Two-step sucrose density gradient centrifugation was used to isolate the plasma membrane of a myeloid leukemia cell line (Ml). Calspectin (or fodrin) was identified in the Triton-insoluble fraction from the plasma membrane, and the molecular size and actin- and calmodulin-binding activity were studied. During differentiation of this cell line, which accompanied the induction of cell motility and phagocytic activity, the membrane-bound actin increased dramatically, whereas calspectin increased only slightly. Therefore, calspectin does not appear to have a major function in the increased binding of actin filaments to the plasma membrane, a requirement for the induction of cell motility.
D000135:Acid Phosphatase / Q000032:analysis; D000199:Actins / Q000032:analysis*; D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000032:analysis; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000032:analysis*; D003576:Electron Transport Complex IV / Q000032:analysis; D005954:Glucosephosphate Dehydrogenase / Q000032:analysis; D007951:Leukemia, Myeloid / Q000032:analysis* / Q000648:ultrastructure; D008565:Membrane Proteins / Q000032:analysis*; D051379:Mice; D009363:Neoplasm Proteins / Q000032:analysis*; D010587:Phagocytosis; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis; D013049:Spectrin / Q000032:analysis*
D000199:Actins; D002148:Calmodulin-Binding Proteins; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D013049:Spectrin; D005954:Glucosephosphate Dehydrogenase; D003576:Electron Transport Complex IV; D000135:Acid Phosphatase; D000254:Sodium-Potassium-Exchanging ATPase