BIOL 330 Lecture Notes - Lecture 10: Exon Junction Complex, Small Nuclear Rna, Alternative Splicing
Document Summary
Introduction: rna splicing- the process of excising introns from rna and connecting the exons into a continuous mrna, heterogeneous nuclear rna (hnrna)- rna that comprises transcripts of nuclear genes made by rna polymerase ii. Nuclear splice junctions are short sequences: splice sites are the sequence immediately surrounding the exon-intron boundaries. U1, u2, u4, u5, and u6: together with some additional proteins, the snrnps form the spliceosome. Alternative splicing is a rule, rather than an exception, in multicellular eukaryotes: specific exons or exon sequences may be excluded or included in the mrna products by using alternative splicing sites. Alternative splicing contributes to structural and functional diversity of gene products. Rna binding proteins, many of which may be developmentally regulated and/or expressed in a tissue-specific manner: the rate of transcription can directly affect the outcome of alternative splicing. There are 2 mechanisms that ensure mutually exclusive splicing: steric hindrance- two sites are too close together, combination of major and minor splice sites.
