首页 | 本学科首页   官方微博 | 高级检索  
   检索      


The T-cell receptor zeta chain contains a GTP/GDP binding site.
Authors:M E Peter  C Hall  A Rühlmann  J Sancho  C Terhorst
Institution:Laboratory of Molecular Immunology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.
Abstract:In a search for nucleotide binding proteins associated with the T-cell receptor (TCR)-CD3 complex, a novel labeling technique involving introduction of alpha-32P]GTP or alpha-32P]ATP into permeabilized cells followed by in situ periodate oxidation was developed. To test the method we first demonstrated that p21ras and other classical GTP binding proteins could be labeled in a GTP-specific manner. In human T lymphocytes the TCR zeta chain was found to be specifically labeled by GTPoxi but not by ATPoxi or CTPoxi. Labeling kinetics and competition experiments demonstrated that zeta had a capacity to bind GTP and GDP but not GMP or ATP. Proteolytic cleavage experiments identified lysine 128 as the GTP crosslinking site. This result was confirmed by studies using oligonucleotide-directed mutagenesis. Lysine residues 128, 135 and 149 were each replaced by arginine and glycine 134 by valine and mutated proteins were expressed in CHO cells. Labeling of mutants K128R and G134V was abrogated whereas mutant proteins K135R and K148R could still be specifically crosslinked to GTP. We conclude that Lys128 and Gly134 are part of a GTP/GDP binding site suggesting that zeta is a unique GTP/GDP binding structure.
Keywords:
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号