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U8 Small Nucleolar RNA
In molecular biology, U8 small nucleolar RNA (also known as SNORD118) is the RNA component of a small RNA:protein complex (the U8 snoRNP) which is required for biogenesis of mature large subunit ribosomal RNAs, 5.8S rRNA, 5.8S and 28S rRNAs. More specifically, U8 is a non-coding RNA (ncRNA) molecule which functions in the modification of other small nuclear RNAs (snRNAs). This type of modifying RNA is usually located in the nucleolus of the eukaryotic cell which is a major site of snRNA biogenesis. It is known as a snoRNA, small nucleolar RNA (snoRNA) and also often referred to as a guide RNA. snoRNA U8 belongs to the SnoRNA#C.2FD box, C/D box class of snoRNAs which contain the conserved sequence motifs known as the C box (UGAUGA) and the D box (CUGA). Most of the members of the box C/D family function in directing site-specific 2'-O-methylation of substrate RNAs. U8 RNA genes have been identified in human, mouse, rat and the amphibian ''Xenopus laevis''. References External l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Structure
Protein secondary structure is the three dimensional form of ''local segments'' of proteins. The two most common secondary structural elements are alpha helices and beta sheets, though beta turns and omega loops occur as well. Secondary structure elements typically spontaneously form as an intermediate before the protein folds into its three dimensional tertiary structure. Secondary structure is formally defined by the pattern of hydrogen bonds between the amino hydrogen and carboxyl oxygen atoms in the peptide backbone. Secondary structure may alternatively be defined based on the regular pattern of backbone dihedral angles in a particular region of the Ramachandran plot regardless of whether it has the correct hydrogen bonds. The concept of secondary structure was first introduced by Kaj Ulrik Linderstrøm-Lang at Stanford in 1952. Other types of biopolymers such as nucleic acids also possess characteristic secondary structures. Types The most common secondary st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Non-coding RNA
A non-coding RNA (ncRNA) is a functional RNA molecule that is not translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally important types of non-coding RNAs include transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), as well as small RNAs such as microRNAs, siRNAs, piRNAs, snoRNAs, snRNAs, exRNAs, scaRNAs and the long ncRNAs such as Xist and HOTAIR. The number of non-coding RNAs within the human genome is unknown; however, recent transcriptomic and bioinformatic studies suggest that there are thousands of non-coding transcripts. Many of the newly identified ncRNAs have not been validated for their function. There is no consensus in the literature on how much of non-coding transcription is functional. Some researchers have argued that many ncRNAs are non-functional (sometimes referred to as "junk RNA"), spurious transcriptions. Others, however, disagree, arguing instead ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular And Cellular Biology
''Molecular and Cellular Biology'' is a biweekly peer-reviewed scientific journal covering all aspects of molecular and cellular biology. It is published by the American Society for Microbiology and the editor-in-chief is Peter Tontonoz (University of California, Los Angeles). It was established in 1981. The h-index (1981-2021) is 338. Abstracting and indexing The journal is abstracted and indexed in: According to the ''Journal Citation Reports'', the journal has a 2021 impact factor The impact factor (IF) or journal impact factor (JIF) of an academic journal is a scientometric index calculated by Clarivate that reflects the yearly mean number of citations of articles published in the last two years in a given journal, as ... of 5.069. References External links * Molecular and cellular biology journals Delayed open access journals Publications established in 1981 English-language journals Biweekly journals American Society for Microbiology academic journals [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2'-O-methylation
2'-''O''-methylation is a common nucleoside modification of RNA, where a methyl group is added to the 2' hydroxyl of the ribose moiety of a nucleoside, producing a methoxy group. 2'-''O''-methylated nucleosides are mostly found in ribosomal RNA and small nuclear RNA and occur in the functionally essential regions of the ribosome and spliceosome. Currently, about 1210 2'-''O''-methylations (2'-''O''-Me) have been identified in mammals and yeast and deposited in RMBase (RNA Modification Base) database. Having chemical properties intermediate between RNA and DNA, 2'-''O''-methylation is presumed to have been one of the reactive group of RNA molecules on early earth that would have given rise to DNA. A novel method, Nm-REP-seq, was developed for enriching ribose methylations by using RNA exoribonuclease (Mycoplasma genitalium RNase R, MgR) and periodate oxidation reactivity to eliminate 2'-hydroxylated (2'-OH) nucleosides. Nm-REP-seq utilizes two orthogonal lines of evidences for t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SnoRNA
In molecular biology, Small nucleolar RNAs (snoRNAs) are a class of small RNA molecules that primarily guide chemical modifications of other RNAs, mainly ribosomal RNAs, transfer RNAs and small nuclear RNAs. There are two main classes of snoRNA, the C/D box snoRNAs, which are associated with methylation, and the H/ACA box snoRNAs, which are associated with pseudouridylation. SnoRNAs are commonly referred to as guide RNAs but should not be confused with the guide RNAs that direct RNA editing in trypanosomes. snoRNA guided modifications After transcription, nascent rRNA molecules (termed pre-rRNA) undergo a series of processing steps to generate the mature rRNA molecule. Prior to cleavage by exo- and endonucleases, the pre-rRNA undergoes a complex pattern of nucleoside modifications. These include methylations and pseudouridylations, guided by snoRNAs. *Methylation is the attachment or substitution of a methyl group onto various substrates. The rRNA of humans contain approxima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleolus
The nucleolus (, plural: nucleoli ) is the largest structure in the nucleus of eukaryotic cells. It is best known as the site of ribosome biogenesis, which is the synthesis of ribosomes. The nucleolus also participates in the formation of signal recognition particles and plays a role in the cell's response to stress. Nucleoli are made of proteins, DNA and RNA, and form around specific chromosomal regions called nucleolar organizing regions. Malfunction of nucleoli can be the cause of several human conditions called "nucleolopathies" and the nucleolus is being investigated as a target for cancer chemotherapy. History The nucleolus was identified by bright-field microscopy during the 1830s. Little was known about the function of the nucleolus until 1964, when a study of nucleoli by John Gurdon and Donald Brown in the African clawed frog '' Xenopus laevis'' generated increasing interest in the function and detailed structure of the nucleolus. They found that 25% of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small Nuclear RNA
Small nuclear RNA (snRNA) is a class of small RNA molecules that are found within the splicing speckles and Cajal bodies of the cell nucleus in eukaryotic cells. The length of an average snRNA is approximately 150 nucleotides. They are transcribed by either RNA polymerase II or RNA polymerase III. Their primary function is in the processing of pre- messenger RNA ( hnRNA) in the nucleus. They have also been shown to aid in the regulation of transcription factors ( 7SK RNA) or RNA polymerase II (B2 RNA), and maintaining the telomeres. snRNA are always associated with a set of specific proteins, and the complexes are referred to as small nuclear ribonucleoproteins (snRNP, often pronounced "snurps"). Each snRNP particle is composed of a snRNA component and several snRNP-specific proteins (including Sm proteins, a family of nuclear proteins). The most common human snRNA components of these complexes are known, respectively, as: U1 spliceosomal RNA, U2 spliceosomal RNA, U4 splic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
28S RRNA
Crazy Eights is a shedding-type card game for two to seven players and the best known American member of the Eights Group which also includes Pig and Spoons. The object of the game is to be the first player to discard all of their cards. The game is similar to Switch and Mau Mau. Originally this was played primarily by children with the left over cards not used in Euchre. Now a standard 52-card deck is used when there are five or fewer players. When there are more than five players, two decks are shuffled together and all 104 cards are used. Origins The game first appeared as ''Eights'' in the 1930s, and the name ''Crazy Eights'' dates to the 1940s, derived from the United States military designation for discharge of mentally unstable soldiers, Section 8. It may have derived from the German game of Mau-Mau. There are many variations of the basic game, under names including ''Craits'', '' Last Card'', ''Switch'', and ''Black Jack''. Bartok, Mao, Taki, and Uno add further e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sequence Conservation
In evolutionary biology, conserved sequences are identical or similar Sequence (biology), sequences in nucleic acids (DNA sequence, DNA and RNA) or peptide sequence, proteins across species (homology (biology)#Orthology, orthologous sequences), or within a genome (homology (biology)#Paralogy, paralogous sequences), or between donor and receptor taxa (Sequence homology#Xenology, xenologous sequences). Conservation indicates that a sequence has been maintained by natural selection. A highly conserved sequence is one that has remained relatively unchanged far back up the phylogenetic tree, and hence far back in geological time. Examples of highly conserved sequences include the Ribosomal RNA, RNA components of ribosomes present in all domain (biology), domains of life, the homeobox sequences widespread amongst Eukaryotes, and the tmRNA in Bacteria. The study of sequence conservation overlaps with the fields of genomics, proteomics, evolutionary biology, phylogenetics, bioinformatics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal RNA
Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and translate the latter into proteins. Ribosomal RNA is the predominant form of RNA found in most cells; it makes up about 80% of cellular RNA despite never being translated into proteins itself. Ribosomes are composed of approximately 60% rRNA and 40% ribosomal proteins by mass. Structure Although the primary structure of rRNA sequences can vary across organisms, base-pairing within these sequences commonly forms stem-loop configurations. The length and position of these rRNA stem-loops allow them to create three-dimensio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
