Cell motility: proline-rich proteins promote protrusions

Many proline-rich proteins participate in delivering actin monomers to spec ific cellular locations where actin-rich membrane protrusions, such as ruff les, filopodia and microspikes, are formed. These protrusions are necessary for cell motility, Actin monomer is usually delivered to the site of polym erization in the form of profilactin - a complex of G-actin with a polyprol ine-binding protein, profilin. Here, we describe proline-rich proteins invo lved in regulating actin polymerization and classify them according to thei r role in recruiting profilin to the membrane.