T-cell antigen receptor (TCR)-alpha/beta heterodimer formation is a prerequisite for association of CD3-zeta 2 into functionally competent TCR.CD3 complexes.
In order to study the relationship between assembly, surface expression, and signal transduction of the alpha/beta T-cell antigen receptor-CD3 complex (TCR.CD3), a series of T-cell mutants with a partial block in assembly of the complex was generated. By chemical mutagenesis, we produced somatic cell variants of the human T-leukemia cell line, HPB-ALL, which expressed low amounts of TCR.CD3 complexes on their surface. RNA and protein analyses demonstrated that most variants synthesized normal amounts of the individual members of the complex, i.e. TCR-alpha, TCR-beta, CD3-gamma, -delta, -epsilon, and -zeta. In these variants, less than 10% of the TCR.CD3 complexes inside the cell contained the CD3-zeta 2 homodimer due to an intrinsic deficiency in the formation of the TCR-alpha/beta heterodimer. The low level of assembly of CD3-zeta 2 into the TCR.CD3 complex and an additional decrease in the rate of export of the TCR.CD3 complex from the endoplasmic reticulum explained the low level of expression of alpha/beta receptors on the surface of these mutants. Only cells with the complete set of subunits of the TCR.CD3 complex on their surface were capable of transducing CD3-mediated signals. The results presented in this paper indicate that TCR-alpha/beta heterodimer formation is an obligatory requirement for assemblage of CD3-zeta 2 into a functionally competent TCR.CD3 complex.
Sancho
J
J
Laboratory of Molecular Immunology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115.
Chatila
T
T
Wong
R C
RC
Hall
C
C
Blumberg
R
R
Alarcon
B
B
Geha
R S
RS
Terhorst
C
C
D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D015152:Blotting, Northern; D017252:CD3 Complex; D002460:Cell Line; D015180:Electrophoresis, Gel, Two-Dimensional; D005434:Flow Cytometry; D014644:Genetic Variation; D006801:Humans; D046911:Macromolecular Substances; D009154:Mutation; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D013601:T-Lymphocytes / Q000276:immunology
D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell