FcεRI Signaling in Specialized Membrane Domains

Field, Kenneth A.; Holowka, David; Baird, Barbara

doi:10.1007/978-1-4612-2154-8_9

Cited by 2 publications

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“…We have proposed a novel model for this process in which specialized membrane domains enriched in Lyn mediate this phosphorylation that occurs after the aggregation-dependent association of Fc⑀RI with these domains (5). This model is consistent with our findings that the rapid association of Fc⑀RI with these domains does not depend on receptor phosphorylation (6).…”

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Structural Aspects of the Association of FcεRI with Detergent-resistant Membranes

Field¹,

Holowka

Baird

1999

Journal of Biological Chemistry

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We recently showed that aggregation of the high affinity IgE receptor on mast cells, Fc⑀RI, causes this immunoreceptor to associate rapidly with specialized regions of the plasma membrane, where it is phosphorylated by the tyrosine kinase Lyn. In this study, we further characterize the detergent sensitivity of this association on rat basophilic leukemia-2H3 mast cells, and we compare the capacity of structural variants of Fc⑀RI and other receptors to undergo this association. We show that this interaction is not mediated by the ␤ subunit of the receptor or the cytoplasmic tail of the ␥ subunit, both of which are involved in signaling. Using chimeric receptor constructs, we found that the extracellular segment of the Fc⑀RI ␣ subunit was not sufficient to mediate this association, implicating Fc⑀RI ␣ and/or ␥ transmembrane segments. To determine the specificity of this interaction, we compared the association of several other receptors. Interleukin-1 type I receptors on Chinese hamster ovary cells and ␣ 4 integrins on rat basophilic leukemia cells showed little or no association with isolated membrane domains, both before and after aggregation on the cells. In contrast, interleukin-2 receptor ␣ (Tac) on Chinese hamster ovary cells exhibited aggregationdependent membrane domain association similar to Fc⑀RI. These results provide insights into the structural basis and selectivity of lipid-mediated interactions between certain transmembrane receptors and detergent-resistant membranes.Multichain immune recognition receptors present on hematopoietic cells interact with Src family protein tyrosine kinases (PTKs) 1 as an early signaling step (1). Aggregation of the high affinity receptor for IgE, Fc⑀RI, results in phosphorylation of the ␤ and ␥ 2 subunits of this receptor by the Src family PTK, Lyn (2, 3). Lyn phosphorylation of the immunoreceptor tyrosine-based activation motif (ITAM) within Fc⑀RI ␥ subunits allows the ZAP-70-related PTK, Syk, to associate with the receptor via its two Src homology 2 domains (1, 2). This recruitment and consequent activation of Syk leads to further downstream signaling, including phosphorylation and activation of phospholipase C␥, mobilization of intracellular calcium, and activation of protein kinase C (4). In mast cells and basophils, which both express Fc⑀RI, these cascades result in the exocytosis of preformed granules containing histamine and other vasoactive compounds, as well as other cellular responses.The phosphorylation of Fc⑀RI by Lyn is a critical event in receptor activation, but the mechanism by which receptor aggregation stimulates this event is not well understood. We have proposed a novel model for this process in which specialized membrane domains enriched in Lyn mediate this phosphorylation that occurs after the aggregation-dependent association of Fc⑀RI with these domains (5). This model is consistent with our findings that the rapid association of Fc⑀RI with these domains does not depend on receptor phosphorylation (6). It is strongly supported by preferential tyros...

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