Additional glycoprotein defects in Bernard-Soulier's syndrome: confirmation of genetic basis by parental analysis.
The glycoprotein profile of Bernard-Soulier platelets was examined by labeling washed platelets with periodate 3H-sodium borohydride, a procedure that labels greater than 30 glycoproteins on the membrane surface of normal platelets. Three Bernard-Soulier patients were studied; two were siblings and the third was unrelated. The platelet protein and glycoprotein profiles were evaluated under nonreduced and reduced conditions using 5%-15% exponential SDS-polyacrylamide gel electrophoresis. The two siblings completely lacked glycoprotein Ib (GPIb). The unrelated patient had congruent to 7% of the normal level. This was confirmed by two-dimensional nonreduced-reduced SDS-polyacrylamide gel electrophoresis, a procedure that allows clear separation of the disulfide-linked subunits of GPIb, GPIb alpha (mol wt 145,000), and GPIb beta (mol wt 25,000) from other membrane glycoproteins. On one-dimensional analysis, Bernard-Soulier's syndrome (BSS) platelets also lacked the peripheral membrane glycoprotein, GPV (mol wt 82,000) and a low molecular weight glycoprotein, GPIX, (nonreduced or reduced, mol wt congruent to 22,000). The two-dimensional gel system also revealed the absence of a minor glycoprotein with a molecular weight of congruent to 100,000 (GP 100). Quantitation of these proteins solubilized from electrophoretograms showed that the siblings' parents had congruent to 50% levels of GPIb, GPIX, and GP 100. A monoclonal antibody against glycoprotein Ib, FMC 25, was negative by immunofluorescence against Bernard-Soulier platelets and immuneprecipitated both GP Ib and GPIX from Triton X100 solubilized, labeled platelets. The combined results suggest that the apparent genetic absence of multiple proteins in Bernard-Soulier platelets is due, in part, to the presence in normal platelets of a tight membrane complex between glycoprotein Ib and at least one of the other absent glycoproteins.
D000293:Adolescent; D000328:Adult; D001791:Blood Platelet Disorders / Q000175:diagnosis / Q000235:genetics*; D001792:Blood Platelets / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006023:Glycoproteins / Q000172:deficiency*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000172:deficiency; D010504:Periodic Acid; D010980:Platelet Membrane Glycoproteins; D012967:Sodium Dodecyl Sulfate; D013577:Syndrome
D006023:Glycoproteins; D008565:Membrane Proteins; D010980:Platelet Membrane Glycoproteins; D010504:Periodic Acid; D012967:Sodium Dodecyl Sulfate