title: Building a pseudo-atomic model of the anaphase-promoting complex.
abstract: The anaphase-promoting complex (APC/C) is a large E3 ubiquitin ligase that regulates progression through specific stages of the cell cycle by coordinating the ubiquitin-dependent degradation of cell-cycle regulatory proteins. Depending on the species, the active form of the APC/C consists of 14-15 different proteins that assemble into a 20-subunit complex with a mass of approximately 1.3 MDa. A hybrid approach of single-particle electron microscopy and protein crystallography of individual APC/C subunits has been applied to generate pseudo-atomic models of various functional states of the complex. Three approaches for assigning regions of the EM-derived APC/C density map to specific APC/C subunits are described. This information was used to dock atomic models of APC/C subunits, determined either by protein crystallography or homology modelling, to specific regions of the APC/C EM map, allowing the generation of a pseudo-atomic model corresponding to 80% of the entire complex.
authors.affiliation: Division of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, England.
authors.forename: Kiran
authors.initials: K
authors.lastname: Kulkarni
authors.forename: Ziguo
authors.initials: Z
authors.lastname: Zhang
authors.forename: Leifu
authors.initials: L
authors.lastname: Chang
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Paula C A
authors.initials: PC
authors.lastname: da Fonseca
authors.forename: David
authors.initials: D
authors.lastname: Barford
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome / Q000737:chemistry* / Q000648:ultrastructure; D064189:Apc1 Subunit, Anaphase-Promoting Complex-Cyclosome / Q000737:chemistry* / Q000648:ultrastructure; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid
chemical_list: C577335:ANAPC1 protein, human; D064189:Apc1 Subunit, Anaphase-Promoting Complex-Cyclosome; D029701:Saccharomyces cerevisiae Proteins; D064173:Anaphase-Promoting Complex-Cyclosome
keywords: anaphase-promoting complex; pseudo-atomic model; single-particle electron microscopy