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：2003
卷号：100
期号：6
页码：3263-3268
DOI：10.1073/pnas.0538058100
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Most of the substrates degraded by the proteasome are marked with polyubiquitin chains. However, there are a limited number of examples of nonubiquitinated proteins that are degraded by the proteasome. Here, we describe the degradation of the retinoblastoma family of tumor suppressor proteins by the proteasome in the absence of polyubiquitination. The retinoblastoma protein (p105), p107, and p130 are each targeted for degradation by the pp71 protein, which is encoded by the UL82 gene of human cytomegalovirus. It functions to direct their degradation in the absence of other viral proteins. While the pp71-mediated degradation of the retinoblastoma family of proteins requires proteasome function, it occurs without the attachment of ubiquitin to the substrates and in the absence of a functioning ubiquitin-conjugation system.
