| SF3B4 | |||||||||||||||||||||||||||||||||||||||||||||||||||
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| Identifiers | |||||||||||||||||||||||||||||||||||||||||||||||||||
| Aliases | SF3B4 , AFD1, Hsh49, SAP49, SF3b49, splicing factor 3b subunit 4 | ||||||||||||||||||||||||||||||||||||||||||||||||||
| External IDs | OMIM: 605593; MGI: 109580; HomoloGene: 134086; GeneCards: SF3B4; OMA:SF3B4 - orthologs | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Splicing factor 3B subunit 4 is a protein that in humans is encoded by the SF3B4 gene. [5] [6]
This gene encodes one of four subunits of the splicing factor 3b. The protein encoded by this gene cross-links to a region in the pre-mRNA immediately upstream of the branchpoint sequence in pre-mRNA in the prespliceosomal complex A. It also may be involved in the assembly of the B, C and E spliceosomal complexes. In addition to RNA-binding activity, this protein interacts directly and highly specifically with subunit 2 of the splicing factor 3B. This protein contains two N-terminal RNA-recognition motifs (RRMs), consistent with the observation that it binds directly to pre-mRNA. [6]
In 2012, Canadian researchers belonging to the FORGE (Finding of Rare disease GEnes) consortium identified new dominant mutations in SF3B4 as the cause of Nager syndrome, a rare type of mandibulofacial dysostosis with associated limb malformations. [7]
SF3B4 has been shown to interact with CDC5L, [8] BMPR1A [9] and SF3B2. [5] [10]
A spliceosome is a large ribonucleoprotein (RNP) complex found primarily within the nucleus of eukaryotic cells. The spliceosome is assembled from small nuclear RNAs (snRNA) and numerous proteins. Small nuclear RNA (snRNA) molecules bind to specific proteins to form a small nuclear ribonucleoprotein complex, which in turn combines with other snRNPs to form a large ribonucleoprotein complex called a spliceosome. The spliceosome removes introns from a transcribed pre-mRNA, a type of primary transcript. This process is generally referred to as splicing. An analogy is a film editor, who selectively cuts out irrelevant or incorrect material from the initial film and sends the cleaned-up version to the director for the final cut.
snRNPs, or small nuclear ribonucleoproteins, are RNA-protein complexes that combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs. The action of snRNPs is essential to the removal of introns from pre-mRNA, a critical aspect of post-transcriptional modification of RNA, occurring only in the nucleus of eukaryotic cells. Additionally, U7 snRNP is not involved in splicing at all, as U7 snRNP is responsible for processing the 3′ stem-loop of histone pre-mRNA.
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 or RNA polymerase II, and maintaining the telomeres.
The minor spliceosome is a ribonucleoprotein complex that catalyses the removal (splicing) of an atypical class of spliceosomal introns (U12-type) from messenger RNAs in some clades of eukaryotes. This process is called noncanonical splicing, as opposed to U2-dependent canonical splicing. U12-type introns represent less than 1% of all introns in human cells. However they are found in genes performing essential cellular functions.
The U11 snRNA is an important non-coding RNA in the minor spliceosome protein complex, which activates the alternative splicing mechanism. The minor spliceosome is associated with similar protein components as the major spliceosome. It uses U11 snRNA to recognize the 5' splice site while U12 snRNA binds to the branchpoint to recognize the 3' splice site.
U1 spliceosomal RNA is the small nuclear RNA (snRNA) component of U1 snRNP, an RNA-protein complex that combines with other snRNPs, unmodified pre-mRNA, and various other proteins to assemble a spliceosome, a large RNA-protein molecular complex upon which splicing of pre-mRNA occurs. Splicing, or the removal of introns, is a major aspect of post-transcriptional modification, and takes place only in the nucleus of eukaryotes.
U2 spliceosomal snRNAs are a species of small nuclear RNA (snRNA) molecules found in the major spliceosomal (Sm) machinery of virtually all eukaryotic organisms. In vivo, U2 snRNA along with its associated polypeptides assemble to produce the U2 small nuclear ribonucleoprotein (snRNP), an essential component of the major spliceosomal complex. The major spliceosomal-splicing pathway is occasionally referred to as U2 dependent, based on a class of Sm intron—found in mRNA primary transcripts—that are recognized exclusively by the U2 snRNP during early stages of spliceosomal assembly. In addition to U2 dependent intron recognition, U2 snRNA has been theorized to serve a catalytic role in the chemistry of pre-RNA splicing as well. Similar to ribosomal RNAs (rRNAs), Sm snRNAs must mediate both RNA:RNA and RNA:protein contacts and hence have evolved specialized, highly conserved, primary and secondary structural elements to facilitate these types of interactions.
The U4 small nuclear Ribo-Nucleic Acid is a non-coding RNA component of the major or U2-dependent spliceosome – a eukaryotic molecular machine involved in the splicing of pre-messenger RNA (pre-mRNA). It forms a duplex with U6, and with each splicing round, it is displaced from the U6 snRNA in an ATP-dependent manner, allowing U6 to re-fold and create the active site for splicing catalysis. A recycling process involving protein Brr2 releases U4 from U6, while protein Prp24 re-anneals U4 and U6. The crystal structure of a 5′ stem-loop of U4 in complex with a binding protein has been solved.
U6 snRNA is the non-coding small nuclear RNA (snRNA) component of U6 snRNP, an RNA-protein complex that combines with other snRNPs, unmodified pre-mRNA, and various other proteins to assemble a spliceosome, a large RNA-protein molecular complex that catalyzes the excision of introns from pre-mRNA. Splicing, or the removal of introns, is a major aspect of post-transcriptional modification and takes place only in the nucleus of eukaryotes.
snRNP70 also known as U1 small nuclear ribonucleoprotein 70 kDa is a protein that in humans is encoded by the SNRNP70 gene. snRNP70 is a small nuclear ribonucleoprotein that associates with U1 spliceosomal RNA, forming the U1snRNP a core component of the spliceosome. The U1-70K protein and other components of the spliceosome complex form detergent-insoluble aggregates in both sporadic and familial human cases of Alzheimer's disease. U1-70K co-localizes with Tau in neurofibrillary tangles in Alzheimer's disease.
Splicing factor U2AF 35 kDa subunit is a protein that in humans is encoded by the U2AF1 gene.
Splicing factor 3 subunit 1 is a protein that in humans is encoded by the SF3A1 gene.
Splicing factor 3B subunit 1 is a protein that in humans is encoded by the SF3B1 gene.
Splicing factor 3A subunit 2 is a protein that in humans is encoded by the SF3A2 gene.
Splicing factor 3B subunit 2 is a protein that in humans is encoded by the SF3B2 gene.
Splicing factor 3B subunit 3 is a protein that in humans is encoded by the SF3B3 gene.
U2 small nuclear ribonucleoprotein B is a protein that in humans is encoded by the SNRPB2 gene.
Splicing factor 3B subunit 6, is a protein encoded by SF3B6 gene in vertebrates.
Probable ATP-dependent RNA helicase DDX46 is an enzyme that in humans is encoded by the DDX46 gene.
Kiyoshi Nagai was a Japanese structural biologist at the MRC Laboratory of Molecular Biology Cambridge, UK. He was known for his work on the mechanism of RNA splicing and structures of the spliceosome.
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