ERM family members as molecular linkers between the cell surface glycoprotein CD44 and actin-based cytoskeletons.
The ERM family members, ezrin, radixin, and moesin, localizing just beneath the plasma membranes, are thought to be involved in the actin filament/plasma membrane association. To identify the integral membrane protein directly associated with ERM family members, we performed immunoprecipitation studies using antimoesin mAb and cultured baby hamster kidney (BHK) cells metabolically labeled with [35S]methionine or surface-labeled with biotin. The results indicated that moesin is directly associated with a 140-kD integral membrane protein. Using BHK cells as antigens, we obtained a mAb that recognized the 140-kD membrane protein. We next cloned a cDNA encoding the 140-kD membrane protein and identified it as CD44, a broadly distributed cell surface glycoprotein. Immunoprecipitation with various anti-CD44 mAbs showed that ezrin and radixin, as well as moesin, are associated with CD44, not only in BHK cells, but also in mouse L fibroblasts. Furthermore, immunofluorescence microscopy revealed that in both BHK and L cells, the Triton X-100-insoluble CD44 is precisely colocalized with ERM family members. We concluded that ERM family members work as molecular linkers between the cytoplasmic domain of CD44 and actin-based cytoskeletons.
Tsukita
S
S
Department of Information Physiology, National Institute for Physiological Sciences, Aichi, Japan.
Oishi
K
K
Sato
N
N
Sagara
J
J
Kawai
A
A
Tsukita
S
S
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001798:Blood Proteins / Q000032:analysis / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D002460:Cell Line; D006224:Cricetinae; D003598:Cytoskeletal Proteins; D003599:Cytoskeleton / Q000737:chemistry / Q000378:metabolism*; D018076:DNA, Complementary / Q000032:analysis; D000939:Epitopes / Q000235:genetics / Q000276:immunology; D018960:Hyaluronan Receptors; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D051379:Mice; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000032:analysis / Q000378:metabolism*; D011233:Precipitin Tests; D011506:Proteins / Q000032:analysis / Q000378:metabolism*; D011820:Rabies virus / Q000737:chemistry / Q000276:immunology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D016201:Receptors, Lymphocyte Homing / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000276:immunology; D017422:Sequence Analysis, DNA; D000099149:Ezrin
D000199:Actins; D000911:Antibodies, Monoclonal; D001798:Blood Proteins; D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D000939:Epitopes; D018960:Hyaluronan Receptors; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010750:Phosphoproteins; D011506:Proteins; D011956:Receptors, Cell Surface; D016201:Receptors, Lymphocyte Homing; D011993:Recombinant Fusion Proteins; D000099149:Ezrin; C071058:moesin; C071776:radixin