Mammalian mediator subunit mMED8 is an Elongin BC-interacting protein that can assemble with Cul2 and Rbx1 to reconstitute a ubiquitin ligase.
Proc Natl Acad Sci U S A
; 99(16): 10353-8, 2002 Aug 06.
Article
em En
| MEDLINE
| ID: mdl-12149480
ABSTRACT
The heterodimeric Elongin BC complex has been shown to interact in vitro and in cells with a conserved BC-box motif found in an increasing number of proteins including RNA polymerase II elongation factor Elongin A, suppressor of cytokine signaling (SOCS)-box proteins, and the von Hippel-Lindau tumor suppressor protein. Recently, the Elongin BC complex was found to function as an adaptor that links these BC-box proteins to a module composed of Cullin family members Cul2 or Cul5 and RING-H2 finger protein Rbx1 to reconstitute a family of E3 ubiquitin ligases that activate ubiquitylation by the E2 ubiquitin-conjugating enzyme Ubc5. As part of our effort to understand the functions of Elongin BC-based ubiquitin ligases, we exploited a modified yeast two-hybrid screen to identify a mammalian BC-box protein similar in sequence to Saccharomyces cerevisiae Mediator subunit Med8p. In this report we demonstrate (i) that mammalian MED8 is a subunit of the mammalian Mediator complex and (ii) that MED8 can assemble with Elongins B and C, Cul2, and Rbx1 to reconstitute a ubiquitin ligase. Taken together, our findings are consistent with the model that MED8 could function to recruit ubiquitin ligase activity directly to the RNA polymerase II transcriptional machinery.
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Base de dados:
MEDLINE
Assunto principal:
Fatores de Transcrição
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Proteínas de Ciclo Celular
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Proteínas de Saccharomyces cerevisiae
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Enzimas de Conjugação de Ubiquitina
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Ubiquitina-Proteína Ligases
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Proteínas Culina
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Ligases
Idioma:
En
Ano de publicação:
2002
Tipo de documento:
Article