Differential signaling through the Ig‐α and Ig‐β components of the B cell antigen receptor

European Journal of Immunology - Tập 23 Số 4 - Trang 911-916 - 1993
Kwang‐Myong Kim1,2, Gottfried Alber1,3, Peter Weiser1, Michael Reth1
1Max-Planck Institut für Immunbiologie, Freiburg
2Recipient of a fellowship from the Alexander von Humboldt Foundation.
3Recipient of a “Habilitation stipend” fellowship from the Deutsche Forschungsgemeinschaft.

Tóm tắt

AbstractThe B cell antigen receptor is a complex containing the antigen‐binding immunoglobulin molecules and the Ig‐α/Ig‐β heterodimer which presumably connects the B cell antigen receptor to intracellular signaling components. To analyze the functional properties of the cytoplasmic parts of the B cell antigen receptor, we used the K46 B lymphoma line (IgG2a, χ) to express chimeric molecules composed of the extracellular and transmembrane part of the CD8α molecule and the cytoplasmic sequence of either the Ig‐α (CD8α/Ig‐α), the Ig‐β (CD8α/Ig‐β) protein or the membrane‐bound γ2a heavy chain (CD8α/γ2a). From these three types of chimeric molecules only CD8α/Ig‐α and CD8α/Ig‐β, but not CD8α/γ2a, could transduce signals, thus providing the first evidence that the cytoplasmic tail of Ig‐α and Ig‐β have a signaling capacity. After cross‐linking with anti‐CD8α antibodies, both molecules induced a similar increase in intracellular free calcium ion and in MAP kinase phosphorylation. Protein tyrosine kinases, however, were strongly activated via the CD8α/Ig‐α and only marginally via the CD8α/Ig‐β molecule. This suggests that the Ig‐α and Ig‐β proteins have distinct roles during signal transduction through the B cell antigen receptor.

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European Journal of Immunology

Tập 23 Số 4

911-916

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