title: alpha-Actinin and vinculin in normal and thrombasthenic platelets.
abstract: Recently, the contractile protein alpha-actinin was identified in normal human platelets by its antigenic cross-reaction with a monospecific antibody to purified muscle alpha-actinin. In this study, we extend that preliminary identification of platelet alpha-actinin. Amino acid analysis, one-dimensional peptide maps, and silver stain analysis on polyacrylamide gels demonstrate that human platelet alpha-actinin shows a greater degree of similarity to smooth muscle alpha-actinin than to striated muscle alpha-actinin. There is no evidence to suggest that alpha-actinin is a glycoprotein. In addition, we find that thrombasthenic platelets, which are deficient in glycoproteins IIb and IIIa (GPIIb and GPIIIa) contain normal amounts of alpha-actinin, confirming the recent finding that alpha-actinin and GPIIIa are different proteins in human platelets. We demonstrate that both normal and thrombasthenic platelets also contain vinculin, a 130,000-dalton polypeptide found in many cell types at sites of end-on attachment of microfilaments to the plasma membrane. Thus, the thrombasthenic defect in GPIIb and GPIIIa does not diminish the content of either alpha-actinin or vinculin.
mesh_terms: D000185:Actinin / Q000097:blood*; D000596:Amino Acids / Q000032:analysis / Q000097:blood; D000818:Animals; D001791:Blood Platelet Disorders / Q000097:blood*; D001792:Blood Platelets / Q000032:analysis* / Q000502:physiology; D002645:Chickens; D005895:Gizzard, Avian / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis; D009124:Muscle Proteins / Q000097:blood*; D009130:Muscle, Smooth / Q000032:analysis; D010455:Peptides / Q000032:analysis / Q000097:blood; D010980:Platelet Membrane Glycoproteins; D016596:Vinculin
chemical_list: D000596:Amino Acids; D006023:Glycoproteins; D008565:Membrane Proteins; D009124:Muscle Proteins; D010455:Peptides; D010980:Platelet Membrane Glycoproteins; D000185:Actinin; D016596:Vinculin