Localization of the coactivator Cdh1 and the cullin subunit Apc2 in a cryo-electron microscopy model of vertebrate APC/C.
Mol Cell
; 20(6): 867-79, 2005 Dec 22.
Article
em En
| MEDLINE
| ID: mdl-16364912
ABSTRACT
The anaphase-promoting complex/cyclosome (APC/C) is a ubiquitin ligase with essential functions in mitosis, meiosis, and G1 phase of the cell cycle. APC/C recognizes substrates via coactivator proteins such as Cdh1, and bound substrates are ubiquitinated by E2 enzymes that interact with a hetero-dimer of the RING subunit Apc11 and the cullin Apc2. We have obtained three-dimensional (3D) models of human and Xenopus APC/C by angular reconstitution and random conical tilt (RCT) analyses of negatively stained cryo-electron microscopy (cryo-EM) preparations, have determined the masses of these particles by scanning transmission electron microscopy (STEM), and have mapped the locations of Cdh1 and Apc2. These proteins are located on the same side of the asymmetric APC/C, implying that this is where substrates are ubiquitinated. We have further identified a large flexible domain in APC/C that adopts a different orientation upon Cdh1 binding. Cdh1 may thus activate APC/C both by recruiting substrates and by inducing conformational changes.
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Base de dados:
MEDLINE
Assunto principal:
Conformação Proteica
/
Subunidades Proteicas
/
Complexos Ubiquitina-Proteína Ligase
/
Ubiquitina-Proteína Ligases
/
Proteínas Culina
Tipo de estudo:
Prognostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Ano de publicação:
2005
Tipo de documento:
Article