Ezrin/radixin/moesin (ERM) proteins bind to a positively charged amino acid cluster in the juxta-membrane cytoplasmic domain of CD44, CD43, and ICAM-2.
CD44 has been identified as a membrane-binding partner for ezrin/radixin/moesin (ERM) proteins, plasma membrane/actin filament cross-linkers. ERM proteins, however, are not necessarily colocalized with CD44 in tissues, but with CD43 and ICAM-2 in some types of cells. We found that glutathione-S-transferase fusion proteins with the cytoplasmic domain of CD43 and ... ICAM-2, as well as CD44, bound to moesin in vitro. The regions responsible for the in vitro binding of CD43 and CD44 to moesin were narrowed down to their juxta-membrane 20-30-amino acid sequences in the cytoplasmic domain. These sequences and the cytoplasmic domain of ICAM-2 (28 amino acids) were all characterized by the positively charged amino acid clusters. When E-cadherin chimeric molecules bearing these positively charged amino acid clusters of CD44, CD43, or ICAM-2 were expressed in mouse L fibroblasts, they were co-concentrated with ERM proteins at microvilli, whereas those lacking these clusters were diffusely distributed on the cell surface. The specific binding of ERM proteins to the juxta-membrane positively charged amino acid clusters of CD44, CD43, and ICAM-2 was confirmed by immunoprecipitation and site-directed mutagenesis. From these findings, we conclude that ERM proteins bind to integral membrane proteins bearing a positively charged amino acid cluster in their juxta-membrane cytoplasmic domain.
Mesh Terms:
Amino Acid Sequence, Amino Acids, Animals, Antigens, CD, Antigens, CD43, Antigens, CD44, Binding Sites, Blood Proteins, Cadherins, Cell Adhesion Molecules, Cells, Cultured, Cytoplasm, Cytoskeletal Proteins, Glutathione Transferase, L Cells (Cell Line), Membrane Proteins, Mice, Microfilament Proteins, Microvilli, Molecular Sequence Data, Phosphoproteins, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Proteins, Recombinant Fusion Proteins, Sequence Homology, Amino Acid, Sialoglycoproteins, Transfection
Amino Acid Sequence, Amino Acids, Animals, Antigens, CD, Antigens, CD43, Antigens, CD44, Binding Sites, Blood Proteins, Cadherins, Cell Adhesion Molecules, Cells, Cultured, Cytoplasm, Cytoskeletal Proteins, Glutathione Transferase, L Cells (Cell Line), Membrane Proteins, Mice, Microfilament Proteins, Microvilli, Molecular Sequence Data, Phosphoproteins, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Proteins, Recombinant Fusion Proteins, Sequence Homology, Amino Acid, Sialoglycoproteins, Transfection
J. Cell Biol.
Date: Feb. 23, 1998
PubMed ID: 9472040
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