Caspar-Bauguil S, Arnaud J, Huchenq A, Hein W R, Geisler C, Rubin B
Immunopathology and Human Genetics Center (CIGH), Toulouse, France.
Scand J Immunol. 1994 Sep;40(3):323-36. doi: 10.1111/j.1365-3083.1994.tb03469.x.
In the present study, we have investigated the importance of a phenylalanine (phe195) in the Tcr-C alpha region on Tcr-alpha,beta/CD3 membrane expression. An exchange of phe195 with a tyrosine residue does not affect Tcr/CD3 membrane expression; however, exchange with aspartic acid, histidine or valine prohibit completely Tcr/CD3 membrane expression. This seems to be due to a lack of interaction between mutated Tcr-alpha,beta/CD3-gamma epsilon,delta epsilon complexes and zeta 2 homodimers. The Tcr-C alpha region around phe195 seems together with the same region in the Tcr-C beta region to constitute an interaction site for zeta 2 homodimers. The presence of phe195 on both Tcr-C alpha and Tcr-C beta causes high avidity interaction with zeta 2 homodimers, whereas his195 in both Tcr-C gamma and Tcr-C delta results in an apparently lower avidity interaction with zeta 2 homodimers. It is suggested that the phe195 region (on beta-strand F) and eventually adjacent aromatic amino acid residues on beta-strand B region may play an important role in Tcr-alpha,beta/CD3 membrane expression, in Tcr-alpha,beta/CD3 competition with Tcr-gamma,delta/CD3 complexes for zeta 2 homodimers and in the control of formation of 'mixed' Tcr heterodimers.
在本研究中，我们调查了Tcr-Cα区域中苯丙氨酸（phe195）对Tcr-α,β/CD3膜表达的重要性。将phe195替换为酪氨酸残基不会影响Tcr/CD3膜表达；然而，替换为天冬氨酸、组氨酸或缬氨酸则会完全抑制Tcr/CD3膜表达。这似乎是由于突变的Tcr-α,β/CD3-γε,δε复合物与ζ2同二聚体之间缺乏相互作用。phe195周围的Tcr-Cα区域似乎与Tcr-Cβ区域的相同区域一起构成了ζ2同二聚体的相互作用位点。Tcr-Cα和Tcr-Cβ上均存在phe195会导致与ζ2同二聚体的高亲和力相互作用，而Tcr-Cγ和Tcr-Cδ上的his195与ζ2同二聚体相互作用的亲和力明显较低。有人提出，phe195区域（位于β链F上）以及β链B区域最终相邻的芳香族氨基酸残基可能在Tcr-α,β/CD3膜表达、Tcr-α,β/CD3与Tcr-γ,δ/CD3复合物竞争ζ2同二聚体以及控制“混合”Tcr异二聚体的形成中发挥重要作用。
