TRBP is a protein important for the formation of the RISC complex. Which of the following would you expect in cells with null mutations in TRBP? a. Reduced siRNA-mediated mRNA degradation
b. Increased miRNA-mediated translational repression
c. Increased deadenylase-mediated mRNA degradation
d. Reduced proteasome-mediated protein degradation

a. Reduced siRNA-mediated mRNA degradation

Explanation:

The TRBP (transactivation response element RNA-binding protein) is an RNA-binding protein that forms the Dicer complex, which is involved in epigenetic pathways such as those mediated by the RNA interference (RNAi) mechanism. RNAi is a key process where small non-coding RNAs such as, for example, small interfering RNAs (siRNAs) and microRNAs (miRNAs) can inhibit target gene expression at posttranscriptional level by different mechanisms (including the degradation of target mRNAs). A null mutation of this cofactor will alter the Dicer complex, thereby also affecting RNAi pathways mediated by small interfering RNAs.