The biological activity of natural and mutant pTalpha alleles.
beta selection is a major checkpoint in early thymocyte differentiation, mediated by successful expression of the pre-T cell receptor (TCR) comprising the TCRbeta chain, CD3 proteins, and a surrogate TCRalpha chain, pTalpha. The mechanism of action of the pre-TCR is unresolved. In humans and mice, the pTalpha gene encodes two RNAs, pTalpha(a), and a substantially truncated form, pTalpha(b). This study shows that both are biologically active in their capacity to rescue multiple thymocyte defects in pTalpha(-/-) mice. Further active alleles of pTalpha include one that lacks both the major ectodomain and much of the long cytoplasmic tail (which is unique among antigen receptor chains), and another in which the cytoplasmic tail is substituted with the short tail of TCR Calpha. Thus, very little of the pTalpha chain is required for function. These data support a hypothesis that the primary role of pTalpha is to stabilize the pre-TCR, and that much of the conserved structure of pTalpha probably plays a critical regulatory role.
Gibbons
D
D
Guy's King's St. Thomas' Medical School, Guy's Hospital, London Bridge, London SE1 9RT, United Kingdom.
Douglas
N C
NC
Barber
D F
DF
Liu
Q
Q
Sullo
R
R
Geng
L
L
Fehling
H J
HJ
von Boehmer
H
H
Hayday
A C
AC
D000818:Animals; D001483:Base Sequence; D017931:DNA Primers; D005434:Flow Cytometry; D019673:Genes, T-Cell Receptor alpha; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011493:Protein Kinase C / Q000378:metabolism; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000235:genetics / Q000276:immunology; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D017384:Sequence Deletion; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology
D017931:DNA Primers; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D016693:Receptors, Antigen, T-Cell, alpha-beta; D011994:Recombinant Proteins; D011493:Protein Kinase C