BIOB10Y3 Lecture Notes - Spliceosome, Snrnp, Intron
Document Summary
Pre-mrnas become associated with ribonucleoproteins (protein-rna complexes) that aid in the removal of introns: mature rna is then transported out of the nucleus to the cytosol. Self-splicing introns fungal mitochondria, plant chloroplasts and several bacteria/archaea: known as group ii introns, they fold into a complex structure. Eukaryotic mrnas are similar in structure to type ii introns but are not self-splicing require several small nuclear rnas (snrnas) and their associated proteins: snrnas + associated proteins = snrnps ( snurps ) When hnrnas are synthesized in the nucleus, they become associated w/ a large macromolecular complex known as the spliceosome made up of several snrnps that assemble onto the pre-mrna. U2 and u6 base pair (u6 is catalytically active) U5 snrna keeps the free 5" exon in place and also interacts with the 3" exon in the second step of the u6 catalyzed reaction, the lariat is released and the 2 exons are joined together.
