Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two new sialoglycoproteins, glycophorin B and glycophorin C, were isolated from erythrocyte membranes by extraction with lithium diiodosalicylate, partition in aqueous phenol, gel filtration in detergent, and preparative polyacrylamide gel electrophoresis in sodium dodecyl sulfate. The two proteins were characterized by amino acid and carbohydrate analysis, separation of tryptic peptides, and isolation and purification of the amino terminal glycopeptide from each polypeptide chain. Glycophorin B is found in two forms in electrophoretograms of normal erythrocyte membranes, corresponding to monomer and dimer, as has been similarly described for glycophorin A. By using antibodies to a carboxy terminal determinant of glycophorin A, and direct staining of gels with antibodies and 125I-protein A from Staph. aureus, as well as by two-dimensional immunoelectrophoreis, only the two known forms of glycophorin A are detectable. The data confirm and extend the notion that the sialoglycoproteins in human red cells are dimeric molecules which are either preformed in the membrane or which can readily be generated in vitro. Only glycophorin A and glycophorin C are sensitive to trypsin while in situ in the intact red blood cells.
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PMID:Glycophorins A, B, and C: a family of sialoglycoproteins. Isolation and preliminary characterization of trypsin derived peptides. 73 12

Invasion of erythrocytes by Plasmodium merozoites is an intricate process involving multiple receptor-ligand interactions. The glycophorins and an unknown trypsin sensitive factor are all erythrocyte receptors used during invasion by the major human pathogen Plasmodium falciparum. However, only one erythrocyte receptor, Glycophorin A, has a well-established cognate parasite ligand, the merozoite protein erythrocyte binding antigen-175 (EBA-175). The involvement of several other parasite proteins during invasion have been proposed, but no direct evidence links them with a specific invasion pathway. Here we report the identification and characterization of P. falciparum normocyte binding protein 1 (PfNBP1), an ortholog of Plasmodium vivax reticulocyte binding protein-1. PfNBP1 binds to a sialic acid dependent trypsin-resistant receptor on the erythrocyte surface that appears to be distinct from known invasion receptors. Antibodies against PfNBP1 can inhibit invasion of trypsinized erythrocytes and two P. falciparum strains that express truncated PfNBP1 are unable to invade trypsinized erythrocytes. One of these strain, 7G8, also does not invade Glycophorin B-negative erythrocytes. PfNBP1 therefore defines a novel trypsin-resistant invasion pathway and adds a level of complexity to current models for P. falciparum erythrocyte invasion.
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PMID:A Plasmodium falciparum homologue of Plasmodium vivax reticulocyte binding protein (PvRBP1) defines a trypsin-resistant erythrocyte invasion pathway. 1173 72