Characterization of a third form of the human T cell receptor gamma/delta.
A subpopulation of the CD3+ peripheral T lymphocytes express the TCR-gamma/delta complex. Three distinct TCR-gamma forms that differ in size and in the ability to form a disulfide bridge with the TCR-delta subunit have been described. In this study we analyze the structural difference between the non-disulfide-linked 55-kD and 40-kD TCR-gamma chains. The 40-kD TCR-gamma form contains a smaller polypeptide backbone and carries less carbohydrate compared with the 55-kD TCR-gamma form. A cDNA clone corresponding to the 40-kD TCR-gamma subunit lacks one copy of the second exon of the constant region that is present in the other TCR-gamma subunit. This exon copy encodes part of the connector region that is located between the constant domain and the membrane spanning region. We show that the number of potential N-linked glycan attachment sites are the same for the two TCR-gamma forms. Since these attachment sites are located in the connector region we conclude that the connector region influences the amount of N-linked carbohydrates added to the core TCR-gamma polypeptide, probably by affecting the conformation of the protein. In contrast to the TCR-beta constant region usage, the TCR-gamma constant regions are unequally expressed. Virtually exclusive usage of disulfide-linked complexes were found in some individuals, while both the disulfide-linked and the 40-kD, non-disulfide-linked TCR-gamma forms were detected in other subjects. The ability to distinguish these TCR-gamma/delta forms now makes it possible to study the mechanisms that govern their selection and to determine if they correspond to functionally distinct isotypes.
Hochstenbach
F
F
Division of Tumor Virology, Dana-Faber Cancer Institute, Boston, Massachusetts.
Parker
C
C
McLean
J
J
Gieselmann
V
V
Band
H
H
Bank
I
I
Chess
L
L
Spits
H
H
Strominger
J L
JL
Seidman
J G
JG
D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D006801:Humans; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000235:genetics* / Q000302:isolation & purification; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*
D011948:Receptors, Antigen, T-Cell