Moesin, ezrin, and p205 are actin-binding proteins associated with neutrophil plasma membranes
Pestonjamasp, K. ; Amieva, M. R. ; Strassel, C. P. ; Nauseef, W. M. ; Furthmayr, H. ; Luna, Elizabeth J.
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UMass Chan Affiliations
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Keywords
Animals
Base Sequence
Blood Proteins
Cattle
*Cytoskeletal Proteins
Cytoskeleton
Membrane Proteins
Mice
Microfilament Proteins
Molecular Sequence Data
Neutrophils
Phosphoproteins
Proteins
Sequence Alignment
Sequence Deletion
Sequence Homology
Cell Biology
Life Sciences
Medicine and Health Sciences
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Abstract
Actin-binding proteins in bovine neutrophil plasma membranes were identified using blot overlays with 125I-labeled F-actin. Along with surface-biotinylated proteins, membranes were enriched in major actin-binding polypeptides of 78, 81, and 205 kDa. Binding was specific for F-actin because G-actin did not bind. Further, unlabeled F-actin blocked the binding of 125I-labeled F-actin whereas other acidic biopolymers were relatively ineffective. Binding also was specifically inhibited by myosin subfragment 1, but not by CapZ or plasma gelsolin, suggesting that the membrane proteins, like myosin, bind along the sides of the actin filaments. The 78- and 81-kDa polypeptides were identified as moesin and ezrin, respectively, by co-migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoprecipitation with antibodies specific for moesin and ezrin. Although not present in detectable amounts in bovine neutrophils, radixin (a third and closely related member of this gene family) also bound 125I-labeled F-actin on blot overlays. Experiments with full-length and truncated bacterial fusion proteins localized the actin-binding site in moesin to the extreme carboxy terminus, a highly conserved sequence. Immunofluorescence micrographs of permeabilized cells and cell "footprints" showed moesin co-localization with actin at the cytoplasmic surface of the plasma membrane, consistent with a role as a membrane-actin-linking protein.
Source
Mol Biol Cell. 1995 Mar;6(3):247-59. Link to article on publisher's website