Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Minireview cung cấp cho các bạn kiến thức về ngành y đề tài: The origin recognition complex protein family. | Protein family review The origin recognition complex protein family Bernard P Duncker Igor N Chesnokov and Brendan J McConkey Addresses Department of Biology University of Waterloo Waterloo Ontario N2L 3G1 Canada. Department of Biochemistry and Molecular Genetics University of Alabama at Birmingham School of Medicine Birmingham AL 35294 USA. Correspondence Bernard P Duncker. Email bduncker@ Published 17 March 2009 GenomeBiology 2009 10 214 doi gb-2009-10-3-214 The electronic version of this article is the complete one and can be found online at http 2009 10 3 214 2009 BioMed Central Ltd Summary Origin recognition complex ORC proteins were first discovered as a six-subunit assemblage in budding yeast that promotes the initiation of DNA replication. Orc1-5 appear to be present in all eukaryotes and include both AAA and winged-helix motifs. A sixth protein Orc6 shows no structural similarity to the other ORC proteins and is poorly conserved between budding yeast and most other eukaryotic species. The replication factor Cdc6 has extensive sequence similarity with Orc1 and phylogenetic analysis suggests the genes that encode them may be paralogs. ORC proteins have also been found in the archaea and the bacterial DnaA replication protein has ORC-like functional domains. In budding yeast Orc1-6 are bound to origins of DNA replication throughout the cell cycle. Following association with Cdc6 in G1 phase the sequential hydrolysis of Cdc6- then ORC-bound ATP loads the Mcm2-7 helicase complex onto DNA. Localization of ORC subunits to the kinetochore and centrosome during mitosis and to the cleavage furrow during cytokinesis has been observed in metazoan cells and along with phenotypes observed following knockdown with short interfering RNAs point to additional roles at these cell-cycle stages. In addition ORC proteins function in epigenetic gene silencing through interactions with heterochromatin factors such as Sir1 in budding .
