Cell cycle-dependent expression of mammalian E2-C regulated by the anaphase-promoting complex/cyclosome.
Progression through mitosis requires the precisely timed ubiquitin-dependent degradation of specific substrates. E2-C is a ubiquitin-conjugating enzyme that plays a critical role with anaphase-promoting complex/cyclosome (APC/C) in progression of and exit from M phase. Here we report that mammalian E2-C is expressed in late G(2)/M phase and is degraded as cells exit from M phase. The mammalian E2-C shows an autoubiquitinating activity leading to covalent conjugation to itself with several ubiquitins. The ubiquitination of E2-C is strongly enhanced by APC/C, resulting in the formation of a polyubiquitin chain. The polyubiquitination of mammalian E2-C occurs only when cells exit from M phase. Furthermore, mammalian E2-C contains two putative destruction boxes that are believed to act as recognition motifs for APC/C. The mutation of this motif reduced the polyubiquitination of mammalian E2-C, resulting in its stabilization. These results suggest that mammalian E2-C is itself a substrate of the APC/C-dependent proteolysis machinery, and that the periodic expression of mammalian E2-C may be a novel autoregulatory system for the control of the APC/C activity and its substrate specificity.
Yamanaka
A
A
Department of Molecular and Cellular Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
Hatakeyama
S
S
Kominami
K
K
Kitagawa
M
M
Matsumoto
M
M
Nakayama
K
K
D016475:3T3 Cells; D020816:Amino Acid Motifs; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D002453:Cell Cycle; D006367:HeLa Cells; D006801:Humans; D008025:Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D051379:Mice; D016296:Mutagenesis; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D014162:Transfection; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism
D011993:Recombinant Fusion Proteins; D014452:Ubiquitins; C046288:ubiquitin carrier proteins; D044763:Ubiquitin-Conjugating Enzymes; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases; D008025:Ligases