TheUrokinase receptor, also known asurokinase plasminogen activator surface receptor (uPAR) orCD87 (Cluster ofDifferentiation87), is aprotein encoded in humans by thePLAURgene. It is amultidomainglycoprotein tethered to thecell membrane with aglycosylphosphotidylinositol (GPI) anchor. uPAR was originally identified as a saturable binding site forurokinase (also known as uPA) on the cell surface.
uPAR is a part of theplasminogen activation system, which in the healthy body is involved in tissue reorganization events such asmammary gland involution andwound healing. In order to be able to reorganize tissue, the old tissue must be able to be degraded. An important mechanism in this degradation is theproteolysis cascade initiated by the plasminogen activation system. uPAR binds urokinase and thus restricts plasminogen activation to the immediate vicinity of the cell membrane. When urokinase is bound to the receptor, there is cleavage between the GPI-anchor and the uPAR, releasing a soluble form of the protein known assuPAR.[8][9]
The components of the plasminogen activation system have been found to be highly expressed in manymalignanttumors, indicating that tumors are able to hijack the system, and use it inmetastasis. Thusinhibitors of the various components of the plasminogen activation system have been sought as possible anticancer drugs.[13]
uPAR has been involved in various other non-proteolytic processes related to cancer, such ascell migration,cell cycle regulation, and cell adhesion.
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Overview of all the structural information available in thePDB forUniProt:Q03405 (Human Urokinase plasminogen activator surface receptor) at thePDBe-KB.
