title: Conversion of low-affinity platelet factor 4 to beta-thromboglobulin by plasmin and trypsin.
abstract: Low-affinity platelet factor 4 and beta-thromboglobulin are platelet-secreted proteins that bind with low affinity to heparin. They show extensive immunological cross-reactivity and appear to differ in amino acid sequence only by an amino-terminal peptide unique to low-affinity platelet factor 4. The possibility that beta-thromboglobulin is derived from low-affinity platelet factor 4 by proteolysis was investigated by exposing this protein to the action of plasmin, thrombin and trypsin. While thrombin had no effect, plasmin and trypsin converted low-affinity platelet factor 4 to a species with the same electrophoretic mobility and isoelectric point as beta-thromboglobulin. We conclude that beta-thromboglobulin is a breakdown product of low-affinity platelet factor 4.
mesh_terms: D000595:Amino Acid Sequence; D001609:Beta-Globulins / Q000378:metabolism*; D001779:Blood Coagulation Factors / Q000378:metabolism*; D005341:Fibrinolysin / Q000494:pharmacology*; D006493:Heparin / Q000378:metabolism; D006801:Humans; D010978:Platelet Factor 4 / Q000378:metabolism*; D011485:Protein Binding; D013917:Thrombin / Q000494:pharmacology; D014357:Trypsin; D001620:beta-Thromboglobulin / Q000378:metabolism*
chemical_list: D001609:Beta-Globulins; D001779:Blood Coagulation Factors; D001620:beta-Thromboglobulin; D010978:Platelet Factor 4; D006493:Heparin; D014357:Trypsin; D013917:Thrombin; D005341:Fibrinolysin