PubMed Journals: Genes Cells

  Source:		PMID: 12167161

    		Genes Cells. 2002 Aug;7(8):835-50.
			MBLR, a new RING finger protein resembling
			mammalian Polycomb gene products, is regulated
			by cell cycle-dependent phosphorylation.

			Akasaka T(1), Takahashi N, Suzuki M, Koseki
			H, Bodmer R, Koga H.

			Author Information
			(1) Department of Cellular, Molecular and
			Developmental Biology, University of Michigan,
			830 N University, Ann Arbor, MI 48109-1048,
			USA. takasaka@umich.edu

			BACKGROUND: The RING finger proteins function
			in a variety of fundamental cellular processes.
			The products of some members of the Polycomb
			group (PcG) bear ring finger domains and
			are defined as a subclass of RING finger
			proteins. Among them are Drosophila posterior
			sex combs and suppressor 2 of zeste, whose
			RING fingers are conserved in vertebrate
			PcG proteins Mel18 and Bmi1. RESULTS: We
			have identified a new mammalian RING finger
			protein, termed MBLR due to its structural
			similarity to Mel18 and Bmi1 (Mel18 and
			Bmi1-like RING finger protein). MBLR interacts
			with some PcG proteins: in vitro biochemical
			data support the idea of a direct interaction
			of MBLR's RING finger domain with Ring1B,
			which is highly homologous to one of the
			mammalian PcG genes, Ring1A. We also show
			that MBLR acts as a transcriptional repressor
			in transiently transfected cells, as is
			the case for other PcG proteins. Immunocytochemical
			analysis reveals that MBLR protein is localized
			in a fine-grained distribution throughout
			the nucleoplasm in interphase cultured cells
			and in a fainter diffuse cytoplasmic distribution
			in mitotic cells. In addition, we find that
			serine 32 of MBLR is specifically phosphorylated
			during mitosis, most likely by CDK7, a component
			of the basal transcriptional machinery.
			CONCLUSION: Similarities to previously defined PcG
			proteins suggest that MBLR should be included
			in the same subclass of RING finger proteins
			as Mel18 and Bmi1. Although the biological
			relevance of the cell cycle-related phosphorylation
			remains to be demonstrated, serine 32
			phosphorylation could nevertheless be functionally

			PMID: 12167161 [Indexed for MEDLINE]

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