Biomaterial Database

Methylated cap structures in eukaryotic RNAs: structure, synthesis and functions. 1992

R Reddy, and R Singh, and S Shimba

Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030.

There are more than twenty capped small nuclear RNAs characterized in eukaryotic cells. All the capped RNAs appear to be involved in the processing of other nuclear premessenger or preribosomal RNAs. These RNAs contain either trimethylguanosine (TMG) cap structure or methylated gamma phosphate (Mppp) cap structure. The TMG capped RNAs are capped with M7G during transcription by RNA polymerase II and trimethylated further post-transcriptionally. The Mppp-capped RNAs are transcribed by RNA polymerase III and also capped post-transcriptionally. The cap structures improve the stability of the RNAs and in some cases TMG cap is required for transport of the ribonucleoproteins from cytoplasm to the nucleus. Where tested, the cap structures were not essential for their function in processing other RNAs.

UI	MeSH Term	Description	Entries
D008745	Methylation	Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed)	Methylations
D005057	Eukaryotic Cells	Cells of the higher organisms, containing a true nucleus bounded by a nuclear membrane.	Cell, Eukaryotic,Cells, Eukaryotic,Eukaryotic Cell
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012314	RNA Cap Analogs	Analogs of RNA cap compounds which do not have a positive charge. These compounds inhibit the initiation of translation of both capped and uncapped messenger RNA.	RNA Cap Analogues,Analogs, RNA Cap,Analogues, RNA Cap,Cap Analogs, RNA,Cap Analogues, RNA
D012321	DNA-Directed RNA Polymerases	Enzymes that catalyze DNA template-directed extension of the 3'-end of an RNA strand one nucleotide at a time. They can initiate a chain de novo. In eukaryotes, three forms of the enzyme have been distinguished on the basis of sensitivity to alpha-amanitin, and the type of RNA synthesized. (From Enzyme Nomenclature, 1992).	DNA-Dependent RNA Polymerases,RNA Polymerases,Transcriptases,DNA-Directed RNA Polymerase,RNA Polymerase,Transcriptase,DNA Dependent RNA Polymerases,DNA Directed RNA Polymerase,DNA Directed RNA Polymerases,Polymerase, DNA-Directed RNA,Polymerase, RNA,Polymerases, DNA-Dependent RNA,Polymerases, DNA-Directed RNA,Polymerases, RNA,RNA Polymerase, DNA-Directed,RNA Polymerases, DNA-Dependent,RNA Polymerases, DNA-Directed
D015138	RNA, Nuclear	RNA molecules found in the nucleus either associated with chromosomes or in the nucleoplasm.	Chromosomal RNA,Nuclear RNA,RNA, Chromosomal