A urokinase receptor-associated protein with specific collagen binding properties.
The plasminogen activation cascade system, directed by urokinase and the urokinase receptor, plays a key role in extracellular proteolysis during tissue remodeling. To identify molecular interaction partners of these trigger proteins on the cell, we combined covalent protein cross-linking with mass spectrometry based methods for peptide mapping and primary structure analysis of electrophoretically isolated protein conjugates. A specific tri-molecular complex was observed upon addition of pro-urokinase to human U937 cells. This complex included the urokinase receptor, pro-urokinase, and an unknown, high molecular weight urokinase receptor-associated protein. The tryptic peptide mixture derived from a cross-linked complex of pro-urokinase and the latter protein was analyzed by nanoelectrospray tandem mass spectrometric sequencing. This analysis identified the novel protein as the human homologue of a murine membrane-bound lectin with hitherto unknown function. The human cDNA was cloned and sequenced. The protein, designated uPARAP, is a member of the macrophage mannose receptor protein family and contains a putative collagen-binding (fibronectin type II) domain in addition to 8 C-type carbohydrate recognition domains. It proved capable of binding strongly to a single type of collagen, collagen V. This collagen binding reaction at the exact site of plasminogen activation on the cell may lead to adhesive functions as well as a contribution to cellular degradation of collagen matrices.
Behrendt
N
N
Finsen Laboratory, Rigshospitalet, DK-2100 Copenhagen O, Denmark. niels.behrendt@finsenlab.dk
Jensen
O N
ON
Engelholm
L H
LH
Mørtz
E
E
Mann
M
M
Danø
K
K
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D003094:Collagen / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006031:Glycosylation; D006801:Humans; D037241:Mannose-Binding Lectins; D013058:Mass Spectrometry; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000378:metabolism; D010960:Plasminogen Activators / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011956:Receptors, Cell Surface / Q000737:chemistry* / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator; D017386:Sequence Homology, Amino Acid; D020298:U937 Cells
D003432:Cross-Linking Reagents; C404106:MRC2 protein, human; D037241:Mannose-Binding Lectins; D008562:Membrane Glycoproteins; C524898:PLAUR protein, human; C524899:Plaur protein, mouse; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D003094:Collagen; D010960:Plasminogen Activators