Re: what's the RNA in ribosome used for?

Dear Becky,

your question is quite interesting because recently the scientific
community seemed to finally have answered a part of that. But before 
going straight to the point, I think that we need here a little reminder to 
put a perspective to the whole story.

First of all, the ribosome is the apparatus in the cell that produces 
every proteins. Proteins are used in a variety of way (cell walls, 
production of energy, etc). In order to know which protein to make, the 
ribosome must read a messenger RNA. This RNA encodes a unique 
sequence that is specific for a certain protein (sometimes one 
messenger can gives several protein by a process known as 
splicing). For the records, the messenger is produced in the nucleus 
and the sequence is encoded in the so-called genome. 

So, coming back to the ribosome, it is obvious that it is an essential 
part in the life cycle of any cell. The ribosomes are themselves made 
of proteins and RNA (ribosomal RNA or rRNA). Now, let's talk about 
your question at this point. When people started working on the 
ribosome, it was believed that the proteins were doing the actual job 
of making the proteins from the messenger. The rRNA was believed 
to be only involved in the reading of the messenger. However, when 
significant part of the proteins were removed, the activity was still 
observed. This observation shown that maybe the RNA was the 
catalyst in the reaction but it was not really believed by many scientist 
(I presume !). But recently (last year) a high resolution crystal 
structure of a ribosome's part was obtained by the Steitz lab in Yale. 
They observed that the catalytic core (where the actual job of making 
the protein is performed) was entirely composed of RNA. Therefore, it 
seems that the RNA has the catalytic role in the ribosome which was 
a surprise for a lot of people ! In fact, this is not new since there are 
some RNA that are known to have catalytic property (ribozyme).

These findings have shed light in the RNA community and now 
scientists believe that perhaps RNA catalysis is a much more 
important phenomena than previously believed (perhaps also in 
splicing).

I hope that you understand a bit more about RNA !

Daniel