Disulfide linkage of the zeta and eta chains of the T cell receptor. Possible identification of two structural classes of receptors.
The T cell antigen receptor (TCR) is a multisubunit membrane complex. It consists of two disulfide-linked polymorphic chains (either alpha-beta or gamma-delta heterodimers) which are noncovalently linked to five invariant chains. The CD3-gamma and CD3-delta chains bear N-linked carbohydrates and the CD3-epsilon and zeta chains are nongly-cosylated. Further analysis of the zeta chain in murine T cells demonstrates that it can exist as either a homodimer or disulfide linked to an additional protein with an apparent Mr of 22,000. The partial peptide map of this 22-kDa protein is different than zeta and all of the CD3 components. Like zeta, it has no apparent N-linked carbohydrate chains. We have chosen to refer to this subunit as the eta chain of the TCR. Ninety percent of zeta in cloned and nonclonal populations of T cells exist as a homodimer, and the remainder is found linked to the eta chain. The tight regulation of the zeta-zeta to zeta-eta ratio suggests an important functional role for these structural components of the TCR.
Baniyash
M
M
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, Bethesda, Maryland 20892.
Garcia-Morales
P
P
Bonifacino
J S
JS
Samelson
L E
LE
Klausner
R D
RD
D000818:Animals; D004220:Disulfides / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D007118:Immunoassay; D007163:Immunosorbent Techniques; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000378:metabolism
D004220:Disulfides; D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase