Monomer-dimer dynamics and distribution of GPI-anchored uPAR are determined by cell surface protein assemblies

Valeria R. Caiolfa, Moreno Zamai, Gabriele Malengo, Annapaola Andolfo, Chris D. Madsen, Jason Sutin, Michelle A. Digman, Enrico Gratton, Francesco Blasi, Nicolai Sidenius

Research output: Contribution to journalArticlepeer-review


To search for functional links between glycosylphosphatidylinositol (GPI) protein monomer-oligomer exchange and membrane dynamics and confinement, we studied urokinase plasminogen activator (uPA) receptor (uPAR), a GPI receptor involved in the regulation of cell adhesion, migration, and proliferation. Using a functionally active fluorescent protein-uPAR in live cells, we analyzed the effect that extracellular matrix proteins and uPAR ligands have on uPAR dynamics and dimerization at the cell membrane. Vitronectin directs the recruitment of dimers and slows down the diffusion of the receptors at the basal membrane. The commitment to uPA-plasminogen activator inhibitor type 1-mediated endocytosis and recycling modifies uPAR diffusion and induces an exchange between uPAR monomers and dimers. This exchange is fully reversible. The data demonstrate that cell surface protein assemblies are important in regulating the dynamics and localization of uPAR at the cell membrane and the exchange of monomers and dimers. These results also provide a strong rationale for dynamic studies of GPI-anchored molecules in live cells at steady state and in the absence of cross-linker/clustering agents.

Original languageEnglish
Pages (from-to)1067-1082
Number of pages16
JournalJournal of Cell Biology
Issue number5
Publication statusPublished - Dec 3 2007

ASJC Scopus subject areas

  • Cell Biology


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