Name: Derek Smith
Date: Winter 2013-14
Do we know the biochemical reason as to why and how the mRNA goes and finds a particular ribosome? I know the bottom subunit of the ribosome is made of rRNA, but that interactionwould only be a weak hydrogen bond (if there is even a hydrogen bond that occurs).
Never underestimate the power of a hydrogen bond. Remember, it's essentially the additive force of hydrogen bonding that keeps our DNA double-helix stable and properly base-paired. However, you are correct that the interactions between the mRNA and the small (bottom) ribosomal subunit are usually insufficient for translation to proceed. In both eukaryotic and prokaryotic organisms, the binding and initiation process of translation are assisted by a set of molecules called initiation factors (IFs). Many IFs are riboproteins, meaning that they are composed of both RNA and protein pieces that, together, constitute a functional machine. The IFs bind and orient the mRNA and both ribosomal subunits to coordinate the proper loading of the ribosome onto the mRNA strand. So, no, the interactions of the ribosomal rRNA are not considered sufficient for efficient translation; but the interactions of the IFs with the other translation machinery are often due to hydrogen bonds between the RNA components of the riboproteins, the mRNA, and the ribosome... never underestimate the power of the many, even if they are weak.
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