Biochemical Evidence for the Presence of a Single CD3δ and CD3γ Chain in the Surface T Cell Receptor/CD3 Complex

Qinghua Pan,Ananta S Gollapudi,Vibhuti P Dave

doi:10.1074/jbc.m406145200

Qinghua Pan, Ananta S Gollapudi + Show 1 more

Open Access

https://doi.org/10.1074/jbc.m406145200

Copy DOI

Abstract

The T cell antigen receptor (TCR) consists of an alphabeta heterodimer and associated invariant CD3gamma, delta, epsilon, and zeta chains (TCR/CD3 complex). The general stoichiometry of the receptor complex, which is believed to be one molecule each of TCRalpha, TCRbeta, CD3gamma, and CD3delta and two molecules each of CD3epsilon and CD3zeta, is not clearly understood. Although it has been shown that there are two chains of CD3epsilon and CD3zeta, the stoichiometry of CD3gamma or CD3delta chains in the surface antigen receptor complex has not been determined. In the present study, transgenic mice expressing an altered form of mouse CD3delta and CD3gamma were employed to show that the surface TCR complexes contain one molecule each of CD3delta and CD3gamma. Thymocytes from wild type and CD3 chain transgenic mice on the appropriate knockout background were surface-biotinylated and immunoprecipitated using a specific antibody. The immunoprecipitates were resolved in two dimensions under nonreducing/reducing conditions to determine the stoichiometry of CD3delta and CD3gamma in the surface antigen receptor complex. Our data clearly show the presence of one molecule each of CD3delta and CD3gamma in the surface TCR/CD3 complex.

Highlights

It has been suggested that engagement of the surface receptor complex by a single molecule of peptide/MHC is sufficient to elicit a cytotoxic T cell response [3]
Using CD3␦ and CD3␥ transgenic mice combined with specific immunoprecipitation of the surface-labeled T cell antigen receptor (TCR)/CD3 complex, we show biochemically that the majority of the surface TCR/CD3 complexes contain a single chain of CD3␦ and CD3␥ per TCR complex
We have attempted to address the stoichiometry of CD3␦ and CD3␥ in the surface TCR/CD3 complex

Summary

Introduction

It has been suggested that engagement of the surface receptor complex by a single molecule of peptide/MHC is sufficient to elicit a cytotoxic T cell response [3]. It has been shown that there could exist at least three molecules of CD3⑀ chain [17] and two molecules of TCR␤ chain (and by extension, the TCR␣ chain) [17, 18] Based on these data, a decameric model of TCR/CD3 complex stoichiometry has been proposed [19]. A decameric model of TCR/CD3 complex stoichiometry has been proposed [19] According to this model, there are two molecules each of CD3⑀, CD3␨, TCR␣, and TCR␤ chains and one molecule each of CD3␥ and CD3␦. The presence of four TCR chains and their preferential association with specific CD3 heterodimers raises questions about the stoichiometry of CD3␥ and CD3␦ chains These data suggest that there could be two chains each of CD3␥ and CD3␦ in the receptor complex. Using CD3␦ and CD3␥ transgenic mice combined with specific immunoprecipitation of the surface-labeled TCR/CD3 complex, we show biochemically that the majority of the surface TCR/CD3 complexes contain a single chain of CD3␦ and CD3␥ per TCR complex

Methods

Results

Conclusion