Localization of a PlA1 epitope to the amino terminal 66 residues of platelet glycoprotein IIIa.
A platelet glycoprotein (GP) IIIa epitope library was constructed by insertion of randomly cleaved GPIIIa cDNA fragments in the prokaryotic expression vector lambda gt22 and screened with purified anti-PlA1 antibodies for clones expressing a PlA1 epitope. Five independent clones were isolated and characterized by nucleotide sequencing. The smallest anti-PlA1 reactive clone obtained encoded the amino terminal 66 residues of mature GPIIIa. Substitution of leucine33 (PlA1) with a proline33 (PlA2) by in vitro mutagenesis resulted in the loss of anti-PlA1 reactivity; however, this clone still reacted with anti-GPIIIa polyclonal antibodies. These data indicate that a PlA1 alloantigenic epitope is located within a small, unglycosylated fragment of GPIIIa containing the polymorphism responsible for the PIA phenotype. Furthermore, these results prove that small recombinant mimics of a PlA1 epitope may be synthesized and used for detection of these alloantibodies.
Committee on Vascular Biology, Scripps Research Institute, La Jolla, CA 92037.
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RD
Bowditch
P H
PH
Tani
C E
CE
Halloran
A L
AL
Frelinger
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R
McMillan
M H
MH
Ginsberg
D000483:Alleles; D000595:Amino Acid Sequence; D004252:DNA Mutational Analysis; D000939:Epitopes; D006801:Humans; D008969:Molecular Sequence Data; D010641:Phenotype; D010980:Platelet Membrane Glycoproteins / Q000737:chemistry / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology
D000939:Epitopes; D010980:Platelet Membrane Glycoproteins; D011994:Recombinant Proteins