#Question id: 4119
#Unit 3. Fundamental Processes
Many eukaryotic genes contain a large number of exons. Correct splicing of such genes requires that neighboring exons be ligated to one another; if they are not, exons will be left out. One early proposal suggested that the splicing machinery bound to a splice site at one end of an intron and scanned through the intron to find the splice site at the other end. Such a scanning mechanism would guarantee that an exon was never skipped. This hypothesis was tested with one minigene with a duplicated 5ʹ splice site. Find diagram of the products you expect from minigene if the splicing machinery binds to a 5ʹ splice site and scans toward a 3ʹ splice site.
#Question id: 4118
#Unit 3. Fundamental Processes
If the 5’ splice site sequence changed from 5’- GUAAGU-3’ to 5’-GUAUGU-3’, predict the effect of the sequence change on U1 binding and U6 snRNP binding in an in vitro protein– RNA binding assay.
#Question id: 4117
#Unit 3. Fundamental Processes
The RNA recognition motif (RRM), also called the RNP motif and the RNA-binding domain (RBD), is the most common RNA-binding domain in hnRNP proteins. Choose important characteristics of RBD
a. RRM domain consists of a four-stranded b sheet flanked on one side by two a helices.
b. To interact with the negatively charged RNA phosphates, the b sheet forms a positively charged surface
c. The 45-residue KH motif is also found in the hnRNP and several other RNA-binding proteins
Which of the following statements are correct?
#Question id: 4116
#Unit 3. Fundamental Processes
Proteins that regulate splicing bind to specific sites called exonic (or intronic) splicing enhancers (ESE or ISE) or silencers (ESS and ISS). The former enhances, and the latter repress, splicing at nearby splice sites. Examples of splicing activator and repressors are as
#Question id: 4115
#Unit 3. Fundamental Processes
The possible type of splicing outcome of given gene construct will be
#Question id: 4114
#Unit 3. Fundamental Processes
Splice-site recognition is prone to two kinds of errors. First, splice sites can be skipped, with components bound at, for example, a given 5’ splice site pairing with those at a 3’ site beyond the correct one. Ways in which the accuracy of splice-site selection can be enhanced are as
A. The factors that recognize that site are transferred from the polymerase carboxy-terminal “tail” onto the RNA. Once in place, the 5’ splice site components are poised to interact with those other factors that bind to the next 3’ splice site to be synthesized.
B. SR (serine–arginine-rich) proteins bind to sequences called exonic splicing enhancers (ESEs) within the exons. SR proteins bound to these sites recruit the splicing machinery to the nearby splice sites to ensure correct splicing
C. By recruiting splicing factors to each side of a given exon, this process encourages the so-called “exon definition, contribute to correct splicing
D. Alternative splicing is intentional missplicing mechanism
Which of the following is INCORRECT?