Co-capping of ras proteins with surface immunoglobulins in B lymphocytes

Graziadei, L., Riabowol, K., Bar-Sagi, D. (September 1990) Co-capping of ras proteins with surface immunoglobulins in B lymphocytes. Nature, 347 (6291). pp. 396-400. ISSN 0028-0836 (Print)0028-0836 (Linking)

URL: http://www.ncbi.nlm.nih.gov/pubmed/2120590
DOI: 10.1038/347396a0

Abstract

Cellular ras genes encode a family of membrane-associated proteins (p21ras) that bind guanine nucleotide and possess a low intrinsic GTPase activity. The p21ras proteins are ubiquitously expressed in mammalian cells and are thought to be involved in a growth-promoting signal transduction pathway; their mode of action, however, remains unknown. The ligand-induced movement of cell-surface receptors seems to be a primary event in the transduction of several extracellular signals that control cell growth and differentiation. In B lymphocytes, surface immunoglobulin receptors crosslinked by antibody or other multivalent ligands form aggregates called patches, which then collect into a single assembly, a cap, at one pole of the cell. This process constitutes the initial signal for the activation of a B cell. Here we show by immunofluorescence microscopy that p21ras co-caps with surface immunoglobulin molecules in mouse splenic B lymphocytes. In contrast, no apparent change in the distribution of p21ras occurs during the capping of concanavalin A receptors. The redistribution of p21ras is apparent at the early stages (patching) of immunoglobulin capping and is inhibited by metabolic inhibitors and the cytoskeleton-disrupting agents colchicine and cytochalasin D. The distribution of another membrane-associated guanine nucleotide-binding regulatory protein, the Gi alpha subunit, is not affected by surface immunoglobulin capping. These findings demonstrate that p21ras can migrate in a directed manner along the plasma membrane and suggest that p21ras may be a component of the signalling pathway initiated by the capping of surface immunoglobulin in B lymphocytes.

Item Type: Paper
Uncontrolled Keywords: Animals Antibodies, Anti-Idiotypic/pharmacology Azides/pharmacology B-Lymphocytes/drug effects/*immunology Cell Line, Transformed Colchicine/pharmacology Concanavalin A/pharmacology Cytochalasin D/pharmacology GTP-Binding Proteins/physiology Immunoglobulin Fab Fragments/pharmacology *Immunologic Capping Mice Mice, Inbred BALB C Proto-Oncogene Proteins p21(ras)/*immunology/metabolism Rats Receptors, Antigen, B-Cell/*immunology Receptors, Fc/immunology Signal Transduction Sodium Azide Spleen/cytology
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > G protein > Ras
CSHL Authors:
Communities: CSHL labs
Depositing User: Matt Covey
Date: 27 September 1990
Date Deposited: 04 Apr 2016 19:19
Last Modified: 04 Apr 2016 19:19
Related URLs:
URI: http://repository.cshl.edu/id/eprint/32266

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