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The mammalian profilin isoforms display complementary affinities for PIP 2 and proline‐rich sequences
Author(s) -
Lambrechts Anja,
Verschelde JeanLuc,
Jonckheere Veronique,
Goethals Mark,
Vandekerckhove Joël,
Ampe Christophe
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.3.484
Subject(s) - profilin , biology , biochemistry , gene isoform , proline , actin , amino acid , actin cytoskeleton , cell , cytoskeleton , gene
We present a study on the binding properties of the bovine profilin isoforms to both phosphatidylinositol 4,5‐bisphosphate (PIP 2 ) and proline‐rich peptides derived from vasodilator‐stimulated phosphoprotein (VASP) and cyclase‐associated protein (CAP). Using microfiltration, we show that compared with profilin II, profilin I has a higher affinity for PIP 2 . On the other hand, fluorescence spectroscopy reveals that proline‐rich peptides bind better to profilin II. At micromolar concentrations, profilin II dimerizes upon binding to proline‐rich peptides. Circular dichroism measurements of profilin II reveal a significant conformational change in this protein upon binding of the peptide. We show further that PIP 2 effectively competes for binding of profilin I to poly‐ L ‐proline, since this isoform, but not profilin II, can be eluted from a poly‐ L ‐proline column with PIP 2 . Using affinity chromatography on either profilin isoform, we identified profilin II as the preferred ligand for VASP in bovine brain extracts. The complementary affinities of the profilin isoforms for PIP 2 and the proline‐rich peptides offer the cell an opportunity to direct actin assembly at different subcellular localizations through the same or different signal transduction pathways.