期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：9
页码：3319-3323
DOI：10.1073/pnas.87.9.3319
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The CD3 eta subunit of the T-cell antigen receptor forms a heterodimeric structure with the CD3 zeta subunit in thymus-derived lymphoid cells and is apparently involved in signal transduction through the receptor. Here we report the primary structure of murine CD3 eta as deduced from protein microsequencing and cDNA cloning. The mature protein is divided into three domains: a 9-amino acid extracellular segment, a 21-amino acid transmembrane segment including a negatively charged residue characteristic of CD3 subunits, and a 155-amino acid cytoplasmic tail. The NH2-terminal sequences of CD3 eta and CD3 zeta are identical through amino acid 122 of each mature protein but then diverge in the remainder of their respective COOH-terminal regions, consistent with alternatively spliced products of a common gene. The cytoplasmic domain of CD3 eta is 42 amino acids larger than that of CD3 zeta but lacks one of six potential tyrosine phosphorylation sites as well as a putative nucleotide binding site previously identified in CD3 zeta. These structural features presumably account for the difference between CD3 eta and CD3 zeta function and are consistent with the notion that CD3 eta may be an important component of a T-cell receptor isoform(s) during thymic development.
