Question

Explain the general process of cap-dependent translation (what is the role of the cap?).

Answer 1

Answer :-

Translation initiation is a complex process in which at the starting codon of a mRNA, the ribosomal subunits Met-tRNAi, 40S, and 60S are assembled into an 80S ribosome by eukaryotic initiation factors (eIFs).
One can define the basic mechanism for this process as a sequence of five steps:
1) making of a pool of free 40S subunits;
2) ternary complex development (Met-tRNAi / eIF2/GTP) and subsequently 43S complex (Met-tRNAi / eIF2/GTP, eIF3, eIF1A);
3) MRNA activation by binding the eIF4F cap-binding complex and eIF4A, eIF4B and eIF4H factors with subsequent binding to the 43S complex;
4) Ribosomal scanning and codon reconnaissance start
5) GTP hydrolysis and attachment of the ribosomal subunit 60S.

EIF4E binding cap is often called the rate-limiting step of cap-dependent initiation, and eIF4E concentration is a translational control regulatory nexus. This protein was involved in playing a role during translation in the circularization of mRNA.