In vitro translation and assembly of a complete T cell receptor-CD3 complex

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Item Type:	Article
Title:	In vitro translation and assembly of a complete T cell receptor-CD3 complex
Creators Name:	Huppa, J.B. and Ploegh, H.L.
Abstract:	The T cell receptor for antigen (TCR) is a multisubunit complex that consists of at least seven polypeptides: the clonotypic, disulfide-linked alpha/beta heterodimer that is noncovalently associated with the invariant polypeptides of the CD3 complex (CD3-gamma, -delta, -epsilon) and zeta, a disulfide-linked homodimer. We achieved the complete assembly of the human TCR in an in vitro transcription/translation system supplemented with dog pancreas microsomes by simultaneous translation of the messenger RNAs encoding the TCR-alpha, -beta and CD3-gamma, -delta, -epsilon, and -zeta subunits. CD3-epsilon, one of the subunits that initiates the assembly of the TCR in living cells, forms misfolded, disulfide-linked homooligomers when translated alone. However, co-translation of one of its first binding partners in the course of assembly, CD3-gamma or -delta, led to the expression of mainly monomeric and correctly folded epsilon subunits, the only form we could detect as part of a properly assembled TCR complex. In the absence of these subunits, the ER-resident chaperone calnexin interacted with oligomeric, i.e. misfolded, structures of CD3-epsilon in a glycan-independent manner. A glycan-dependent interaction between CD3-epsilon and calnexin was mediated by CD3-gamma and concerned only monomeric CD3-epsilon complexed with CD3-gamma, but was dispensable for proper folding of CD3-epsilon. We suggest that in addition to its signaling function, CD3-epsilon serves as a monitor for proper subunit assembly of the TCR.
Keywords:	Amino Acid Sequence, CD3 Complex, Calcium-Binding Proteins, Calnexin, Disulfides, Glycosylation, Molecular Sequence Data, Oxidation-Reduction, Peptides, Polymers, Protein Biosynthesis, Protein Folding, Protein Sorting Signals, T-Cell Antigen Receptor-CD3 Complex
Source:	Journal of Experimental Medicine
ISSN:	0022-1007
Publisher:	Rockefeller University Press
Volume:	186
Number:	3
Page Range:	393-403
Date:	4 August 1997
Official Publication:	https://doi.org/10.1084/jem.186.3.393
PubMed:	View item in PubMed

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