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FcεRI-Mediated Recruitment of p53/56lyn to Detergent- Resistant Membrane Domains Accompanies Cellular Signaling
Kenneth A. Field, David Holowka and Barbara Baird
Proceedings of the National Academy of Sciences of the United States of America
Vol. 92, No. 20 (Sep. 26, 1995), pp. 9201-9205
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/2368438
Page Count: 5
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Detergent-resistant plasma membrane structures, such as caveolae, have been implicated in signaling, transport, and vesicle trafficking functions. Using sucrose gradient ultracentrifugation, we have isolated low-density, Triton X-100-insoluble membrane domains from RBL-2H3 mucosal mast cells that contain several markers common to caveolae, including a src-family tyrosine kinase, p53/56lyn. Aggregation of FcεRI, the high-affinity IgE receptor, causes a significant increase in the amount of p53/56lyn associated with these low-density membrane domains. Under our standard conditions for lysis, IgE-FcεRI fractionates with the majority of the solubilized proteins, whereas aggregated receptor complexes are found at a higher density in the gradient. Stimulated translocation of p53/56lyn is accompanied by increased tyrosine phosphorylation of several proteins in the low-density membrane domains as well as enhanced in vitro tyrosine kinase activity toward these proteins and an exogenous substrate. With a lower detergent-to-cell ratio during lysis, significant FcεRI remains associated with these membrane domains, consistent with the ability to coimmunoprecipitate tyrosine kinase activity with FcεRI under similar lysis conditions [Pribluda, V. S., Pribluda, C. \& Metzger, H. (1994) Proc. Natl. Acad. Sci. USA 91, 11246-11250]. These results indicate that specialized membrane domains may be directly involved in the coupling of receptor aggregation to the activation of signaling events.
Proceedings of the National Academy of Sciences of the United States of America © 1995 National Academy of Sciences