Question

Which of the following is the correct sequence of turnover?

(a) Exonucleolytic degradation, decapping, deadenylation

(b) Exonucleolytic degradation, deadenylation and decapping

(c) Deadenylation, decapping, exonucleolytic degradation

(d) Decapping, deadenylation and exonucleolytic degradation

This question was posed to me in an interview for job.

The doubt is from Control of Translation in division Gene Expression : Translation of Cytogenetics

Answer 1

Correct choice is (c) Deadenylation, decapping, exonucleolytic degradation

The best I can explain: The turn-over of the mRNA proceeds in the following sequence- 1^st the poly A tail is degraded i.e. deadenylation. Then the 5’G cap is removed i.e. decapping. The mRNA is degraded by the exonucleases.