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The T-cell antigen receptor (TcR) complex present on most T-cells is formed by a clone-specific disulfide-linked alpha/beta heterodimer noncovalently associated to the CD3 complex, the latter composed of five invariant polypeptides: gamma, delta, epsilon, zeta/zeta, or zeta/eta. The presence of conserved, oppositely charged, amino acids in the predicted transmembrane domains of all the subunits of the TcR.CD3 complex suggests that these residues may have a critical function in the assembly and/or stabilization of the complex. In order to analyze the role of the transmembrane-charged amino acids in the association and cell surface expression of the TcR.CD3 complex, we have carried out site-directed mutagenesis of Lys271 in the transmembrane domain of the TcR beta chain and analyzed the capacity of the altered chain to assemble in a TcR beta-negative T-cell line. Here we show that substitution of this positively charged residue by alanine or glutamine does not prevent cytoplasmic association of alpha and beta chains to form disulfide-linked heterodimers, but does abolish formation of an alpha/beta.CD3 complex and, consequently, its expression on the cell surface.


Journal article


J Biol Chem

Publication Date





4131 - 4135


Antigens, CD, Antigens, Differentiation, T-Lymphocyte, Base Sequence, CD3 Complex, Cell Membrane, Cloning, Molecular, Genes, Humans, Lysine, Macromolecular Substances, Membrane Glycoproteins, Molecular Sequence Data, Mutation, Oligonucleotide Probes, Receptors, Antigen, T-Cell, Restriction Mapping, T-Lymphocytes, Transfection