Guide RNA

Degradation of viral SmaU-guide RNAs directing specific HIV-1 Kim et al. 1999 Nash et al. 2005 ... 

Ma JB, Yuan YR, Meister G et al (2005) Structural basis for 5 -end-specific recognition of guide RNA by the A. fulgidus Piwi protein. Nature 434 666-670... 

Frank F, Sonenberg N, Nagar B (2010) Structural basis for 5 -nucleotide base-specific recognition of guide RNA by human AG02. Nature 465 818-822... 

FIGURE 2 RNA editing of the transcript of the cytochrome oxidase subunit II gene from Trypanosoma brucei mitochondria, (a) Insertion of four U residues (pink) produces a revised reading frame, (b) A special class of guide RNAs, complementary to the edited product, may act as templates for the editing process. 

Telomerase is a reverse transcriptase that copies the DNA sequence of the telomeric repeats from a small guide RNA that is part of the enzyme. Tire first telomerase studied was the relatively abundant enzyme from Tetrahymena. It contains a 159-nucleotide RNA with the sequence 5 -CAACCCCAA-3 at positions 43-51. This sequence is complementary to the 5 -TTGGGG-3 repeat sequence of the Tetrahymena telomeres.450 451 A 127-kDa human protein contains a similar guide RNA with the sequence 5 -CUAACCCUACC-3, which is complementary to the human telomere repeat sequence as is illustrated in Fig. 27-21.452-454 Telomerases455 456 evidently allow the cell to elongate the telomere 5 -ends using the... 

Segment of human telomerase guide RNA in two possible positions... 

The control of telomerase must be important. The enzyme is active in early embryonic cells and some stem cells. However, most normal cells have little or no telomerase activity and lose telomere length throughout their lifespan with eventual growth arrest.448/454/457 On the other hand, excessive telomerase activity may induce cancer.451/458/459 Certain mutations in the telomerase guide RNA can cause greatly increased telomerase activity.459 The control of telomerase is still poorly understood but involves specific telomere-binding proteins 448,454,460-460b... 

Propose a sequence for the guide RNA that directs the editing of precursor RNA to yield the mRNA shown in figure 28.20. 

Darzacq X, Jady BE, Verheggen C, Kiss AM, Bertrand E, Kiss T. Cajal body-specific small nuclear RNAs a novel class of 2 -0-methylation and pseudouridylation guide RNAs. EMBO J. 2002 21(11) 2746-2756. 

Blum B, Bakalara N, Simpson L. A model for RNA editing in kinetoplastid mitochondria guide RNA molecules transcribed from maxicircle DNA provide the edited information. Cell 1990 60(2) 189-198. 

FIG. 1.4 An example of kinetoplastid pan-editing. A portion of the mature T. brucei cytochrome oxidase subunit III is shown above a guide RNA. Uridines inserted via editing are shown in lower case. Insertion of the uridines within the box is directed by a different guide RNA not shown. For details see text and ref. (45). 

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