Covalent binding of guanine nucleotides to the CD3-gamma chain of the T cell receptor/CD3 complex.
Eur J Immunol
; 23(2): 461-6, 1993 Feb.
Article
in En
| MEDLINE
| ID: mdl-8436180
ABSTRACT
In a search for proteins involved in signal transduction through the T cell receptor (TcR/CD3 complex), a recently developed highly efficient method for labeling of nucleotide binding proteins in permeabilized cells was applied. Here, we report that human CD3-gamma could be labeled by periodate-oxidized [alpha-32P] GTP (GTPoxi). In contrast to GTPoxi labeling of CD3-zeta (Peter, M. E., Hall, C., Rühlmann, A., Sancho, J. and Terhorst, C., EMBO J. 1992. 11933), GTP-specific labeling of CD3-gamma reached a maximum when nucleotides were added 60 min prior to the cross-linking reaction. As CD3-gamma did not contain a known consensus sequence for nucleotide binding and since labeling kinetics of CD3-gamma coincided with those of cytosolic GTP-binding proteins, labeling may have been caused by a GTP-binding protein. This putative protein was not T cell specific because labeling of CD3-gamma could also be achieved when expressed in the endoplasmic reticulum of Chinese hamster ovary (CHO) cells. In CHO cells, labeling by GTPoxi took place only when CD3-gamma was associated with CD3-epsilon, whereas labeling could not be established upon association of CD3-gamma with CD3-delta or TcR alpha. The observation that CD3-gamma was labeled without leaving the endoplasmic reticulum led to the hypothesis that the association of CD3-gamma with a GTP-binding protein might be involved in an early step of the TcR/CD3 complex formation or transport.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Receptors, Antigen, T-Cell, gamma-delta
/
Receptor-CD3 Complex, Antigen, T-Cell
/
CD3 Complex
/
Guanine Nucleotides
Limits:
Animals
/
Humans
Language:
En
Journal:
Eur J Immunol
Year:
1993
Document type:
Article