Characterization of an expressed CDS-associated Ti γ-chain reveals Cγ domain polymorphism
Abstract
The majority of human T cells express an antigen receptor consisting of a disulphide-linked heterodimer (Ti) of relative molecular mass 80,000-90,000 (Mr 80-90K) which is noncovalently associated with a set of at least three proteins of Mr 20-28K termed CD3 (Leu4, T3)1-3. Whereas both chains of Ti, an acidic α-chain of Afr 48-54K and a more basic β-chain of Mr 40-44 K, contain variable and constant region domains, the component peptides of CD3 are invariant4-8. Several laboratories have more recently reported the expression of CD3 in association with a novel protein9-12. On the surface of long-term T-cell lines and one thymocyte clone this novel structure consists of a 40K protein noncovalently linked to a 55 or 62K protein9,10 identified as the protein product of the Ti γ-chain gene, a T-cell specific gene which like the Ti α-and Ti β-chain genes undergoes rearrangement of variable (V) and joining (J) region gene segments13-16. On the human T-cell leukaemic line PEER we have detected only a single 55K gly-coprotein associated with CD311. We here demonstrate that an anti-Ti γ-peptide antiserum reacts with the 55K CD3-associated protein on PEER. Most previously described human Ti γ-chain complementary DNA clones encode the products of non-functional rearrangements17,18. One of the Ti γ cDNAs isolated from PEER, however, represents a functional rearrangement reported for the first time in a cell which expresses a Ti γ-chain protein product on the cell surface. Interestingly, a 48-base-pair (bp) sequence in the constant (C) region domain of this functional Ti γ-chain cDNA is triplicated in PEER and duplicated in other cDNAs isolated from PEER and other cell lines.
- Publication:
-
Nature
- Pub Date:
- March 1987
- DOI:
- 10.1038/326085a0
- Bibcode:
- 1987Natur.326...85L