LAYILIN, A NOVEL TALIN-BINDING TRANSMEMBRANE PROTEIN HOMOLOGOUS WITH C-TYPE LECTINS, IS LOCALIZED IN MEMBRANE RUFFLES

Changes in cell morphology and motility are mediated by the actin cyto skeleton. Recent advances in our understanding of the regulators of mi crofilament structure and dynamics have shed light on how these change s are controlled, and efforts continue to define all the structural an d signaling components involved in these processes. The actin cytoskel eton-associated protein talin binds to integrins, vinculin, and actin. We report a new binding partner for talin that we have named layilin, which contains homology with C-type lectins, is present in numerous c ell, lines and tissue extracts, and is expressed on the cell surface. Layilin colocalizes with talin in membrane ruffles, and is recruited t o membrane ruffles in cells induced to migrate in in vitro wounding ex periments and in peripheral ruffles in spreading cells. A ten-amino ac id motif in the layilin cytoplasmic domain is sufficient for talin bin ding. We have identified a short region within talin's amino-terminal 435 amino acids capable of binding to layilin in vitro. This region ov erlaps a binding site for focal adhesion kinase.