Protecting the terminus: t-loops and telomere end-binding proteins.
Telomeric DNA is composed of a region of duplex telomeric tract followed by a single-strand overhang on the 3' G-rich strand. The DNA is packaged by proteins that associate directly with the single- and double-strand regions of the telomeric tract and by their associated proteins. This review discusses the evidence that G-strand overhangs are present on both ends of eukaryotic chromosomes and the steps needed to generate these overhangs. The overhangs are protected by specialized G-overhang-binding protein and/or invasion by the overhang of the duplex region of the telomeric tract to form a structure called a 't-loop'. The G-overhang-binding proteins identified from different species are described, and their properties compared. The data supporting the existence of t-loops at native telomeres is discussed, and the conditions required to promote their in vitro formation are presented.
Wei
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Department of Molecular Genetics, Biochemistry and Microbiology, College of Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, Ohio 45267, USA.
Price
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D000818:Animals; D019926:Cyclin B / Q000737:chemistry / Q000502:physiology; D004261:DNA Replication; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000502:physiology; D006801:Humans; D016615:Telomere / Q000737:chemistry / Q000502:physiology; D034501:Telomere-Binding Proteins / Q000737:chemistry / Q000502:physiology*
D019926:Cyclin B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D034501:Telomere-Binding Proteins