Ligand Interaction between Urokinase-Type Plasminogen Activator and Its Receptor Probed with 8-Anilino-1-naphthalenesulfonate. Evidence for a Hydrophobic Binding Site Exposed Only on the Intact Receptor

Biochemistry ◽  
1994 ◽  
Vol 33 (30) ◽  
pp. 8991-8997 ◽  
Author(s):  
Michael Ploug ◽  
Vincent Ellis ◽  
Keld Danoe
1989 ◽  
Vol 264 (2) ◽  
pp. 1180-1189
Author(s):  
A Estreicher ◽  
A Wohlwend ◽  
D Belin ◽  
W D Schleuning ◽  
J D Vassalli

1987 ◽  
Author(s):  
D Belin ◽  
D Baccino ◽  
A Wohlwend ◽  
A Estreicher ◽  
J Hurate ◽  
...  

Recent cell biological and biochemical studies on the urokinase-type plasminogen activator (u-PA) have revealed an unsuspected property of this protein: it binds with high affinity and specificity to the plasma membrane of a number of cell types. Hence, while the interaction of tissue-type plasminogen activator (t-PA) with fibrin suggests a preferred role for this enzyme in the maintenance of fluidity of the extracellular milieu, the cellular binding of u-PA results in the focalisation of plasmin generation to the close environment of the cell surface; this appears as an optimal configuration if u-PA is to participate in the enzymatic events required for cell migration.The available information on the cellular binding of u-PA can be summarized as follows:1. Human monocytes-macrophages, monocyte-like cell lines, fibroblasts, and a variety of other cell lines all express u-PA binding sites. The number of u-PA binding sites on a given cell type may vary as a function of the functional state of the cells. In some cases all sites are occupied by “endogenous” u-PA.2. Binding does not require u-PA activity, and prou-PA binds with the same affinity as does the active enzyme.3. The Kd for u-PA binding is between 1 and 10×10-10 M. The binding site appears to be specific for u-PA.4. Binding requires the presence of the A chain of u-PA; the growth factor module of the A chain is involved in this interaction.5. Bound enzyme does not dissociate readily, nor is it rapidly endocytosed; most importantly, it retains catalytic activity.Studies in progress are aimed at further defining the u-PA determinants responsible for binding. In this context it is noteworthy that there is a tight species specificity of binding: human and murine u-PA, for instance, bind only to cells of the homologous species. Characterization of the u-PA binding site suggests that it is an integral membrane protein that includes at least one Mf 50.000 polypeptide chain.In addition to allowing for the peri-cellular focalisation of u-PA catalysed proteolysis, expression of the u-PA binding site provides a mecanism whereby one cell type can acquire membrane-bound u-PA activity following secretion of the (pro)enzyme by another cell population. A striking example of this is the binding of u-PA, synthesized by the epithelial layer of the male genital tract, to the head region of murine spermatozoa.


2001 ◽  
Vol 357 (1) ◽  
pp. 289-296 ◽  
Author(s):  
Olav M. ANDERSEN ◽  
Helle H. PETERSEN ◽  
Christian JACOBSEN ◽  
S⊘ren K. MOESTRUP ◽  
Michael ETZERODT ◽  
...  

The low-density-lipoprotein-receptor (LDLR)-related protein (LRP) is composed of several classes of domains, including complement-type repeats (CR), which occur in clusters that contain binding sites for a multitude of different ligands. Each ≈ 40-residue CR domain contains three conserved disulphide linkages and an octahedral Ca2+ cage. LRP is a scavenging receptor for ligands from extracellular fluids, e.g. α2-macroglobulin (α2M)–proteinase complexes, lipoprotein-containing particles and serine proteinase–inhibitor complexes, like the complex between urokinase-type plasminogen activator (uPA) and the plasminogen activator inhibitor-1 (PAI-1). In the present study we analysed the interaction of the uPA–PAI-1 complex with an ensemble of fragments representing a complete overlapping set of two-domain fragments accounting for the ligand-binding cluster II (CR3–CR10) of LRP. By ligand blotting, solid-state competition analysis and surface-plasmon-resonance analysis, we demonstrate binding to multiple CR domains, but show a preferential interaction between the uPA–PAI-1 complex and a two-domain fragment comprising CR domains 5 and 6 of LRP. We demonstrate that surface-exposed aspartic acid and tryptophan residues at identical positions in the two homologous domains, CR5 and CR6 (Asp958,CR5, Asp999,CR6, Trp953,CR5 and Trp994,CR6), are critical for the binding of the complex as well as for the binding of the receptor-associated protein (RAP)–the folding chaperone/escort protein required for transport of LRP to the cell surface. Accordingly, the present work provides (1) an identification of a preferred binding site within LRP CR cluster II; (2) evidence that the uPA–PAI-1 binding site involves residues from two adjacent protein domains; and (3) direct evidence identifying specific residues as important for the binding of uPA–PAI-1 as well as for the binding of RAP.


2001 ◽  
Vol 120 (5) ◽  
pp. A599-A600 ◽  
Author(s):  
L HERSZENYI ◽  
F FARINATI ◽  
G ISTVAN ◽  
M PAOLI ◽  
G ROVERONI ◽  
...  

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