alpha-Actinin and vinculin in normal and thrombasthenic platelets
BG Langer, PA Gonnella and VT Nachmias
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.
Volume 63,
Issue 3,
pp. 606-614,
03/01/1984
Copyright © 1984 by The American Society of Hematology
