Open AccessIdentification and characterization of fragments of major glycoproteins from platelet membrane after chymotrypsin treatment
Author(s) -
McGREGOR John L.,
CLEZARDIN Philippe,
JAMES Elizabeth,
McGREGOR Lilian,
DECHAVANNE Marc,
CLEMETSON Kenneth J.
Publication year - 1985
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1985.tb08812.x
Subject(s) - chemistry , chymotrypsin , platelet , gel electrophoresis , lactoperoxidase , sodium dodecyl sulfate , glycoprotein , biochemistry , platelet membrane glycoprotein , polyacrylamide gel electrophoresis , chromatography , fibrinogen , trypsin , enzyme , biology , peroxidase , immunology
Human platelets were surface‐labeled by the periodate/NaB 3 H 4 method or by lactoperoxidase‐catalysed iodination with 125 I. The labeled platelets were treated with chymotrypsin under conditions known to give platelets which aggregate with fibrinogen without stimulation with ADP. Platelets and supernatant were then analysed by various gel electrophoretic techniques including isoelectricfocusing/sodium dodecyl sulfate‐polyacrylamide gel electrophoresis under reducing or non‐reducing conditions and two‐dimensional non‐reduced/reduced sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by fluorography or indirect autoradiography. Chymotrypsin‐treatment of surface‐labeled platelets degraded the major glycoproteins Ib, IIb and IIIa but also GP 4.9−5.4 120 , GPlc and GPV. The membrane‐bound fragments of GPIb, IIb and IIIa could be identified and also the supernatant fragments of GPIb and GPV. GPIIIa was also cleaved within a loop structure formed by disulfide bond(s). The fact that remnants of both GPIIb and IIIa are left on chymotrypsin‐treated platelets which aggregate spontaneously with fibrinogen may indicate that a complex formed by these remnants constitutes the fibrinogen‐binding site on platelets.