7w5b
From Proteopedia
The cryo-EM structure of human C* complex
Structural highlights
DiseasePRP8_HUMAN Defects in PRPF8 are the cause of retinitis pigmentosa type 13 (RP13) [MIM:600059. RP leads to degeneration of retinal photoreceptor cells. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well. RP13 inheritance is autosomal dominant.[1] [2] [:][3] [4] FunctionPRP8_HUMAN Central component of the spliceosome, which may play a role in aligning the pre-mRNA 5'- and 3'-exons for ligation. Interacts with U5 snRNA, and with pre-mRNA 5'-splice sites in B spliceosomes and 3'-splice sites in C spliceosomes. Publication Abstract from PubMedPre-mRNA splicing involves two sequential reactions: branching and exon ligation. The C complex after branching undergoes remodeling to become the C( *) complex, which executes exon ligation. Here, we report cryo-EM structures of two intermediate human spliceosomal complexes, pre-C( *)-I and pre-C( *)-II, both at 3.6 A. In both structures, the 3' splice site is already docked into the active site, the ensuing 3' exon sequences are anchored on PRP8, and the step II factor FAM192A contacts the duplex between U2 snRNA and the branch site. In the transition of pre-C( *)-I to pre-C( *)-II, the step II factors Cactin, FAM32A, PRKRIP1, and SLU7 are recruited. Notably, the RNA helicase PRP22 is positioned quite differently in the pre-C( *)-I, pre-C( *)-II, and C( *) complexes, suggesting a role in 3' exon binding and proofreading. Together with information on human C and C( *) complexes, our studies recapitulate a molecular choreography of the C-to-C( *) transition, revealing mechanistic insights into exon ligation. Mechanism of exon ligation by human spliceosome.,Zhan X, Lu Y, Zhang X, Yan C, Shi Y Mol Cell. 2022 Aug 4;82(15):2769-2778.e4. doi: 10.1016/j.molcel.2022.05.021. Epub , 2022 Jun 14. PMID:35705093[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also
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