Molecular cloning of effector cell protease receptor-1, a novel cell surface receptor for the protease factor Xa.
Cellular receptors for blood proteases regulate chemotaxis, extracellular proteolysis, and growth behavior of normal and malignant cells. Binding of the coagulation protease factor Xa to leukocytes is contributed by a recently identified molecule, denominated Effector cell Protease Receptor-1 (EPR-1). Monoclonal antibodies were generated against EPR-1+ MOLT13 lymphocytes and selected for reactivity with lymphocyte surface proteins by flow cytometry and with affinity-purified EPR-1 in Western blots. Antibody-based functional cloning of the cDNA for EPR-1 reveals the sequence of a novel molecule encoded by a prominent 1.9-kilobase mRNA. The cDNA predicts a glycoprotein of 337 amino acids, characterized by a unique cysteine-rich extracellular module, a single membrane-spanning domain, and a serine-rich (26%) cytoplasmic tail featuring at least 15 potential phosphorylation sites. Genetically engineered EPR-1 transfectants were recognized by monoclonal antibodies to EPR-1 and bound 125I-factor Xa in a specific and saturable manner (Kd approximately 10-15 nM). In the absence of factor V/Va, EPR-1 transfectants promoted prothrombin activation in a factor Xa concentration-dependent reaction, inhibited by a monoclonal antibody to EPR-1. These findings define EPR-1 as a novel cell surface receptor for factor Xa potentially implicated in protease-dependent cellular effector functions.
Altieri
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Department of Immunology, Scripps Research Institute, La Jolla, California 92037.
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D016466:CHO Cells; D002460:Cell Line; D002846:Chromatography, Affinity; D003001:Cloning, Molecular / Q000379:methods; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D015951:Factor Xa / Q000378:metabolism*; D015723:Gene Library; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D007700:Kinetics; D015458:Leukemia, T-Cell; D007962:Leukocytes / Q000378:metabolism; D008969:Molecular Sequence Data; D010980:Platelet Membrane Glycoproteins / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D011516:Prothrombin / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D000077022:Survivin; D014162:Transfection; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; C107489:BIRC5 protein, human; D018076:DNA, Complementary; D051034:Inhibitor of Apoptosis Proteins; D010980:Platelet Membrane Glycoproteins; D011956:Receptors, Cell Surface; D000077022:Survivin; C045069:factor X receptors; D011516:Prothrombin; D015951:Factor Xa