Belin, D Baccino, D Wohlwend, A Estreicher, A Hurate, J Vassalli, J-D 2018 <jats:p>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.</jats:p><jats:p>The available information on the cellular binding of u-PA can be summarized as follows:</jats:p><jats:p>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.</jats:p><jats:p>2. Binding does not require u-PA activity, and prou-PA binds with the same affinity as does the active enzyme.</jats:p><jats:p>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.</jats:p><jats:p>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.</jats:p><jats:p>5. Bound enzyme does not dissociate readily, nor is it rapidly endocytosed; most importantly, it retains catalytic activity.</jats:p><jats:p>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.</jats:p><jats:p>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.</jats:p> https://sonar.ch/global/documents/54589 eng info:eu-repo/semantics/altIdentifier/doi/10.1055/s-0038-1642957 XIth International Congress on Thrombosis and Haemostasis. - Schattauer GmbH. - 1987 A CELLULAR RECEPTOR FOR UROKINASE-TYPE PLASMINOGEN ACTIVATOR http://purl.org/coar/resource_type/c_6501