Layilin, a novel integral membrane protein, is a hyaluronan receptor.
The actin cytoskeleton plays a significant role in changes of cell shape and motility, and interactions between the actin filaments and the cell membrane are crucial for a variety of cellular processes. Several adaptor proteins, including talin, maintain the cytoskeleton-membrane linkage by binding to integral membrane proteins and to the cytoskeleton. Layilin, a recently characterized transmembrane protein with homology to C-type lectins, is a membrane-binding site for talin in peripheral ruffles of spreading cells. To facilitate studies of layilin's function, we have generated a layilin-Fc fusion protein comprising the extracellular part of layilin joined to human immunoglobulin G heavy chain and used this chimera to identify layilin ligands. Here, we demonstrate that layilin-Fc fusion protein binds to hyaluronan immobilized to Sepharose. Microtiter plate-binding assays, coprecipitation experiments, and staining of sections predigested with different glycosaminoglycan-degrading enzymes and cell adhesion assays all revealed that layilin binds specifically to hyaluronan but not to other tested glycosaminoglycans. Layilin's ability to bind hyaluronan, a ubiquitous extracellular matrix component, reveals an interesting parallel between layilin and CD44, because both can bind to cytoskeleton-membrane linker proteins through their cytoplasmic domains and to hyaluronan through their extracellular domains. This parallelism suggests a role for layilin in cell adhesion and motility.
Bono
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Howard Hughes Medical Institute, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.
Rubin
K
K
Higgins
J M
JM
Hynes
R O
RO
D016475:3T3 Cells; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion; D002460:Cell Line; D006224:Cricetinae; D006025:Glycosaminoglycans / Q000378:metabolism; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000378:metabolism*; D006821:Hyaluronoglucosaminidase / Q000378:metabolism; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000378:metabolism; D008024:Ligands; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D010179:Pancreas / Q000378:metabolism / Q000473:pathology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012995:Solubility; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D006025:Glycosaminoglycans; D018960:Hyaluronan Receptors; D007141:Immunoglobulin Fc Fragments; D008024:Ligands; D008562:Membrane Glycoproteins; D011993:Recombinant Fusion Proteins; C115279:layilin protein, mouse; D006820:Hyaluronic Acid; D006821:Hyaluronoglucosaminidase