Question

In an experiment if you take a stretch of hybridized RNA, and add only eIF4A, eIF4B and eIF4a and eIF4B together what will happen to the band obtained by that fragment under SDS.

(a) Slight rise, no rise, appearance of two bands one on top of original

(b) No rise in all cases but appearance of a 2^nd band on top of 1^st in 3^rd case

(c) Slight rise, slightly more rise, and highest rise

(d) A faint band above the original, only original and a dark band above original

I have been asked this question by my school principal while I was bunking the class.

The origin of the question is Control of Translation topic in section Gene Expression : Translation of Cytogenetics

Answer 1

Right option is (d) A faint band above the original, only original and a dark band above original

To elaborate: Rise in a band is seen only in case of EMSA which is not performed in this experiment. Here eIF4A acts as a helicase separating the dimer into monomer which leads to the formation of an upper band. eIF4B is a promoter of helicase activity of eIF4A in absence of which there is only slight activity.