Question

16. What is the basic strategy used by snRNPs - how specific sites arerecognized and how eventually the catalytic site is formed?

17. What are the “landmarks” for the spliceosomal machinery? How does the spliceosome find splice sites reliably?

18. What are the specific functions of the snRNPs.
19. How does U4 prevent premature splicing activity?
20. What are the functions of the 5’ exon, 3’exon, 5’ splice site, 3’ splice site, branch point, ribozymes, Exonic splicing enhancers (ESEs) and SR proteins, and 5’GU and 3’AG splice sites?
21. Give some scenarios of alternative splicing options.

Answer 1

16).

The snRNPs or small nuclear ribonucleoproteins are the small particles that combine with proteins and pre-mRNA molecules to form “spliceosome.” The snRNPs play a key role in removing the introns from pre-mRNA, which is a key step in the post-transcriptional RNA modification occurring in the eukaryotes.

The RNA present in the snRNP is called, “small nuclear RNA,” due to its small length (about 150 nucleotides). This small nuclear RNA or snRNA gives specificity to the introns and they recognize the critical splicing signaling sequences at the 5’ and 3’ ends of introns. The small nuclear RNA works similar to the ribosomal RNA and it directly acts as an enzyme and also plays a structural role.