Verprolin: A Cool Set of Actin-binding Sites and Some Very HOT Prolines

Spatiotemporal organisation of eukaryotic cells is established and maintained by the cytoskeleton, a highly dynamic and complex network of structural and signalling proteins. Many components of the cytoskeleton are functionally and structurally conserved between humans and yeast. Among these are verprolin (Vrp1p) in yeast and its human ortholog Wiskott-Aldrich syndrome protein (WASP)-interacting protein (WIP). Much of our understanding of the function of these proteins has come from genetic analysis in yeast. Verprolin-deficient yeast cells exhibit defects in cytokinesis, endocytosis, and actin cytoskeleton polarisation. Verprolin binds actin, the yeast ortholog of human WASP (Las17p or Bee1p), and the yeast ortholog of human PSTPIP1 (Hof1p or Cyk2p). We propose that verprolin acts as a chaperone that by transient bimolecular interactions maintains the proper function of its partners. Verprolin-related proteins and partners are implicated in cancer, immunodeficiency, and neurodegeneration. Therefore, elucidating how verprolin functions will have major impacts in cell biology and medicine. (C) 2009 IUBMB IUBMB Life, 61(7): 707-712, 2009