标题：Intracellular transport blockade caused by disruption of the disulfide bridge in the third external domain of major histocompatibility complex class I antigen
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：1986
卷号：83
期号：3
页码：757-761
DOI：10.1073/pnas.83.3.757
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The third external domain of major histocompatibility class I antigens has a highly conserved disulfide bridge between cysteine-203 and cysteine-259. To elucidate the functional significance of this disulfide bridge, we have produced a mutant H-2Ld gene by site-directed mutagenesis in which the codon for cysteine-203 is changed to a codon for serine, which is unable to form a disulfide bridge. The mutant H-2Ld gene was introduced into mouse L cells and its expression has been studied. No measurable expression of the H-2Ld antigen was detected on the cell surface of the transformants by antibody-binding assays. However, a large quantity of the mutant H-2Ld antigen was found in the cytoplasm of the transformants as observed by immunoprecipitation of metabolically labeled lysate and by immunocytochemistry of membrane-permeabilized cells, using an antibody specific for the first external domain of the H-2Ld antigen. The mutant antigen was glycosylated and associated, at least in part, with beta 2-microglobulin. Subcellular fractionation experiments indicated that the transport of the antigen was blocked between the endoplasmic reticulum and the plasma membrane. It is concluded that structural integrity of the third external domain is a prerequisite for intracellular transport of class I antigens. On the basis of these findings we suggest that the domain structure containing the disulfide bridge serves as a signal structure necessary for receptor-mediated intracellular transport and that this requirement is the evolutionary basis for high conservation of similar structures present throughout the immunoglobulin supergene family.
