ScaRNAs in the context of Spliceosome

ScaRNAs in the context of Spliceosome

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⭐ Core Definition: ScaRNAs

Small Cajal body-specific RNAs (scaRNAs) are a class of small nucleolar RNAs (snoRNAs) that specifically localise to the Cajal body, a nuclear organelle (cellular sub-organelle) involved in the biogenesis of small nuclear ribonucleoproteins (snRNPs or snurps). ScaRNAs guide the modification (methylation and pseudouridylation) of RNA polymerase II transcribed spliceosomal RNAs U1, U2, U4, U5 and U12.

The first scaRNA identified was U85. It is unlike typical snoRNAs in that it is a composite C/D box and H/ACA box snoRNAs and can guide both pseudouridylation and 2′-O-methylation. Not all scaRNAs are composite C/D and H/ACA box snoRNA and most scaRNAs are structurally and functionally indistinguishable from snoRNAs, directing ribosomal RNA (rRNA) modification in the nucleolus.

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ScaRNAs in the context of 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 unknown functions, if any. There is no consensus on how much of non-coding transcription is functional: some believe most ncRNAs to be non-functional "junk RNA", spurious transcriptions, while others expect that many non-coding transcripts have functions to be discovered.

View the full Wikipedia page for Non-coding RNA
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LINKED FROM (PARENTS)
← Non-coding RNA ← Non-coding RNAs
LINKS TO (CHILDREN)
Small nucleolar RNA → Cajal body → Cell nucleus → Organelle → SnRNP → Methylation → Pseudouridylation → RNA polymerase II → Transcription (genetics) → Spliceosome → U1 spliceosomal RNA → U2 spliceosomal RNA → U4 spliceosomal RNA → U5 spliceosomal RNA → U12 minor spliceosomal RNA → Ribosomal RNA → Nucleolus →