Nucleolar RNA (snoRNAs) is a class of small RNA molecules direct chemical modification mainly of ribosomal RNA small nuclear RNA, and transfer RNA, the RNA main other. Methylation, there is a major class of snoRNA C / D box snoRNAs 2 and is associated with the H / ACA snoRNAs box that is associated with the pseudouridylation. SnoRNAs is referred to as the guide RNA often, direct RNA is not to be confused with the guide RNA that you want to edit in the trypanosome.
After transfer, (also referred to as pre-rRNA gene) rRNA molecules newborn must undergo a series of processes for the preparation of rRNA molecules mature. RRNA in advance and before separation of the exo-endonuclease to pass a complex pattern of nucleoside change. These include, the pseudouridylations and methylation guided by snoRNAs. Methylation is the addition or substitution of methyl groups on various substrates. I have to fix 115 methyl around the human rRNA. Most of them, is (when the methyl group is bonded to a ribose group) 2’O-ribose methylation.
SnoRNA of each molecule acts as a guide to the individual changes (or two) and just one in the target RNA. Correction, coupled to the at least four molecules of the protein RNA / protein complex small nucleolar ribonucleoprotein (snoRNP) in, I run the snoRNA each. Proteins related to the RNA for each, depending on the type of molecule, (please refer to snoRNA guide families below) snoRNA. SnoRNA molecules aimed to include (a part of 10 to 20 nucleotides) antisense elements complementary to the nucleotide sequence around the bases (nucleotides), to change the pre-RNA molecules. This means snoRNP possible to recognize and bind to the target RNA. The snoRNP, after being connected to the target site of the fusion protein is in the correct physical locations that catalyzes chemical change in the target database.
It is dominated by different families of snoRNPs two different types of two 2 (pseudouridylation and methylation) modification of rRNA. These families are referred to as H / ACA box snoRNAs and snoRNAs anti-C / D box that is based on the presence of sequence motifs that are stored in the snoRNA. There are exceptions out there, H / ACA pseudouridylation members and C / D box methylation guide member is using in general. Members of each household, might vary biosynthesis, structure and function, but each family has been classified by the features in common:. For more information, please refer to the reviews. SnoRNAs can be classified into a small nuclear RNA network.
Conserved sequence motifs two short near the end of each snoRNA 5 ‘and 3’, contains a C (RUGAUGA) D is (CUGA) The C / D box snoRNAs. Usually, short region downstream of the D box and the upstream-side box C (~ 5 nucleotides) form a stem box structure that carries the D box motif and C in the vicinity on the basis of complementarity. The stem box structure, it is essential to the proper fusion snoRNA nucleolar localization is shown. The C / D box snoRNA is many, it contains additional or less of storage copy well, (referred to as the ‘D and’ C) motif of C and D is located in the center of the molecule snoRNA. Conserved region of 10-21 nucleotides upstream of the D box methylation sites complementary to the target RNA can snoRNA to form a double-stranded RNA and RNA. Nucleotides saved four evolutionary changes the target RNA to associate Snu13 (fibrillarin (Nop1p), Nop56p, and Nop58p essential protein is located in the fifth position upstream of the box D “) or (usually box D has. C / D box snoRNAs (a eukaryote, its homologues full L7Ae).), inducing a 2′-O-methylated constituting the core C / D box snoRNP is not shown But it, by directing cleavage of pre-rRNA, processing of rRNA will work C / D box snoRNA of eukaryotic (snoRNA U3), instead.
The W / ACA box snoRNAs, and has a secondary structure that are commonly composed of a single-stranded region of the two, called hairpin hinge hairpin tail structure and two hairpins. I contains a sequence conserved motif W / ACA snoRNAs also known as (ACA) box ACA H and box (consensus ANANNA). Two patterns are arranged in the single-stranded region of the secondary structure. H motif located in the hinge ACA motif is positioned three nucleotides from the 3 ‘end of the sequence of the tail region. Hairpin region includes internal projection called a detection circuit disposed in the antisense guide sequence (bases complementary to the target sequence). Both in terms of, this recognition sequence, to form a complex pseudo-knot with the target RNA (composed of two different branches of the loop region). The saved four evolutionary make up the core of the H / ACA box snoRNP, an essential protein (Nop10p dyskerin (Cbf5p), Gar1p, and Nhp2p), W / ACA box snoRNAs associate. However, in lower eukaryotic cells such as Trypanosoma such, is present in the form of windows and sharp single structure of AGA ACA box in the 3 ‘end of the RNA instead such as RNA.
To RNP RNP formation and pre-RNA component of human telomerase, including the nucleolar localization H / ACA domain of telomerase (hTERC). This, as a result of a partnership with human telomerase, and are involved rare genetic disorder dyskeratosis congenita to (DKC) is important for H / ACA snoRNP. Mutations in the protein components of H / ACA snoRNP result in the reduction of physiological TERC level. It is associated with the pathology behind DCC you think it is strong, to be a disease of poor telomere maintenance mainly.
The unusual use snoRNA U85, two features found pseudouridylation and ribose 2’-O-methylated small nuclear RNA (of snRNA) in the U5. Association with H / ACA box domain and C / D and protein that is specific to each containing Gar1p and (fibrillaring. Has been identified additional information complex snoRNAs. This complex snoRNA is, these complexes each class snoRNA is is called SnoRNAs Cajal body which accumulate in the nucleus organelles were found, are referred to as RNA and Cajal body-specific. and most of the localization box H / ACA snoRNAs boxes nucleolus or C / D It is contrast. modification of U12 and U1, U2, U4, U5 RNA polymerase II RNA transcript spliceosome which has been Y Cajal body localization to be involved in RNA and a Cajal body-specific thereof has been suggested. snoRNAs is the H / ACA box snoRNAs components and C / D is not all.