Previous Article | Next Article ![]()
Journal of Virology, December 2000, p. 11262-11269, Vol. 74, No. 23
Graduate School of Biotechnology, Korea
University, Seoul 136-701, Korea
Received 15 May 2000/Accepted 13 September 2000
The human cytomegalovirus US3, an endoplasmic reticulum
(ER)-resident transmembrane glycoprotein, forms a complex with major histocompatibility complex (MHC) class I molecules and retains them in
the ER, thereby preventing cytolysis by cytotoxic T lymphocytes. To
identify which parts of US3 confine the protein to the ER and which
parts are responsible for the association with MHC class I molecules,
we constructed truncated mutant and chimeric forms in which US3 domains
were exchanged with corresponding domains of CD4 and analyzed them for
their intracellular localization and the ability to associate with MHC
class I molecules. All of the truncated mutant and chimeric proteins
containing the luminal domain of US3 were retained in the ER, while
replacement of the US3 luminal domain with that of CD4 led to cell
surface expression of the chimera. Thus, the luminal domain of US3 was
sufficient for ER retention. Immunolocalization of the US3 glycoprotein
after nocodazole treatment and the observation that the carbohydrate moiety of the US3 glycoprotein was not modified by Golgi enzymes indicated that the ER localization of US3 involved true retention, without recycling through the Golgi. Unlike the ER retention signal, the ability to associate with MHC class I molecules required the transmembrane domain in addition to the luminal domain of US3. Direct
interaction between US3 and MHC class I molecules could be demonstrated
after in vitro translation by coimmunoprecipitation. Together, the
present data indicate that the properties that allow US3 to be
localized in the ER and bind MHC class I molecules are located in
different parts of the molecule.
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Structural and Functional Dissection of Human Cytomegalovirus US3
in Binding Major Histocompatibility Complex Class I Molecules
*
Corresponding author. Mailing address: Graduate School
of Biotechnology, Korea University, 1, 5-ka, Anam-dong, Sungbuk-Gu, Seoul 136-701, Korea. Phone: 82-2-3290-3445. Fax: 82-2-927-9028. E-mail: ksahn{at}mail.korea.ac.kr.
This article has been cited by other articles:
| J. Bacteriol. | Mol. Cell. Biol. | Microbiol. Mol. Biol. Rev. |
|---|
| Clin. Vaccine Immunol. | ALL ASM JOURNALS |
|---|