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 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.
Splicing factor U2AF 65 kDa subunit is a protein that in humans is encoded by the U2AF2 gene.
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.
Small nuclear ribonucleoprotein Sm D1 is a protein that in humans is encoded by the SNRPD1 gene.
Small nuclear ribonucleoprotein-associated proteins B and B' is a protein that in humans is encoded by the SNRPB gene.
Splicing factor U2AF 35 kDa subunit is a protein that in humans is encoded by the U2AF1 gene.
Small nuclear ribonucleoprotein Sm D2 is a protein that in humans is encoded by the SNRPD2 gene. It belongs to the small nuclear ribonucleoprotein core protein family, and is required for pre-mRNA splicing and small nuclear ribonucleoprotein biogenesis. Alternative splicing occurs at this locus and two transcript variants encoding the same protein have been identified.
Splicing factor 3 subunit 1 is a protein that in humans is encoded by the SF3A1 gene.
U1 small nuclear ribonucleoprotein A is a protein that in humans is encoded by the SNRPA gene.
U5 small nuclear ribonucleoprotein 200 kDa helicase is an enzyme that in humans is encoded by the SNRNP200 gene.
Small nuclear ribonucleoprotein F is a protein that in humans is encoded by the SNRPF gene.
Splicing factor 3B subunit 2 is a protein that in humans is encoded by the SF3B2 gene.
Pre-mRNA-processing factor 6 is a protein that in humans is encoded by the PRPF6 gene.
U2 small nuclear ribonucleoprotein A' is a protein that in humans is encoded by the SNRPA1 gene.
U4/U6 small nuclear ribonucleoprotein Prp4 is a protein that in humans is encoded by the PRPF4 gene. The removal of introns from nuclear pre-mRNAs occurs on complexes called spliceosomes, which are made up of 4 small nuclear ribonucleoprotein (snRNP) particles and an undefined number of transiently associated splicing factors. PRPF4 is 1 of several proteins that associate with U4 and U6 snRNPs.[supplied by OMIM]
Peptidyl-prolyl cis-trans isomerase H is an enzyme that in humans is encoded by the PPIH gene.
