During mRNA processing, splicing reactions are initiated in the branch site by which reactive group?
A) the 5'-OH of an uridylate residue
B) the 2'-OH of an adenylate residue
C) the OH of an adenylate residue
D) the OH of a guanosine co-factor
E) the 5'-phosphate of thymidine triphosphate (TTP)

Question

Quizplus · Accepted Answer

The splicing reactions during mRNA processing are initiated at the branch site by the 2'-OH of an adenylate residue. This hydroxyl group attacks the 5' splice site, leading to the formation of the lariat structure in the intron.

During MRNA Processing, Splicing Reactions Are Initiated in the Branch