title: alpha-Actinin and membrane glycoprotein IIIa are different proteins in human blood platelets.
abstract: It has been suggested that a platelet protein that is very similar to muscle alpha-actinin is identical to the membrane glycoprotein IIIa (GPIIIa) of platelets and is responsible for anchoring actin filaments directly into the plasma membrane of platelets. To determine if alpha-actinin and GPIIIa are related in platelets, we analyzed the purified proteins on 5% sodium dodecyl sulfate/polyacrylamide gels. The two proteins differ in mobility in both the unreduced and reduced states, and they stain differently with silver stain. In addition, alpha-actinin is a prominent component of the detergent-insoluble cytoskeletons of platelets, whereas GPIIIa is absent from these structures. By using monospecific antisera to the individual proteins, it was demonstrated that alpha-actinin and GPIIIa are immunologically distinct. We conclude that alpha-actinin and GPIIIa are different proteins in human blood platelets and that it is unlikely that alpha-actinin is an integral membrane protein.
mesh_terms: D000185:Actinin / Q000097:blood* / Q000276:immunology; D001792:Blood Platelets / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D000939:Epitopes; D006023:Glycoproteins / Q000097:blood* / Q000276:immunology; D006801:Humans; D008970:Molecular Weight; D009124:Muscle Proteins / Q000097:blood*; D010980:Platelet Membrane Glycoproteins
chemical_list: D000939:Epitopes; D006023:Glycoproteins; D009124:Muscle Proteins; D010980:Platelet Membrane Glycoproteins; D000185:Actinin