Epidermal growth factor-binding protein activates soluble and receptor-bound single chain urokinase-type plasminogen activator.
Epidermal growth factor-binding protein (EGF-BP) is a serine proteinase that reversibly associates with epidermal growth factor (EGF). We analyzed the reaction of EGF-BP with urokinase type plasminogen activator (u-PA), a serine proteinase that promotes pericellular proteolysis and cellular migration. EGF-BP cleaved single chain u-PA (scu-PA) between Lys158 and Ile159, converting the zymogen into enzymatically active two-chain u-PA (tcu-PA), as shown by SDS-PAGE, N-terminal sequence analysis, and enzymatic assay. The kcat and Km of the activation reaction were (5.6 +/- 0.6) x 10(-2)s-1 and 2.0 +/- 0.3 microM, yielding a catalytic efficiency of 2.8 x 10(4) M-1.s-1. EGF-BP also activated scu-PA bound to receptors on U937 monocytes as demonstrated by the generation of amidase activity against a tcu-PA-specific fluorogenic substrate. By activating scu-PA, EGF-BP may initiate u-PA-dependent cell surface proteolysis and therefore enhance EGF activities that require cellular migration and/or tissue remodeling.
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000595:Amino Acid Sequence; D002478:Cells, Cultured; D010450:Endopeptidases / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator; D012995:Solubility; D014568:Urokinase-Type Plasminogen Activator / Q000737:chemistry / Q000378:metabolism*
D000590:Amino Acid Chloromethyl Ketones; C524898:PLAUR protein, human; D010455:Peptides; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D010450:Endopeptidases; D014568:Urokinase-Type Plasminogen Activator; C040308:phenylalanyl-prolyl-arginine-chloromethyl ketone