Reverse transcriptase

[Paul Schauble]

In article <Pine.SOL.3.91.950505153836.10172B-100000 at corona>,
Patrick O'Neil <patrick at corona> wrote:
> 
> 
> On 5 May 1995, Webb Howell wrote:
> 
> > 
> > Does the enzyme reverse transcriptase cause the action of duplicating 
> > a retrovirus's RNA genome into a DNA version?  Or does a retrovirus 
> 
> Reverse transcriptase's whole purpose in life is to produce a dsDNA copy 
> of a virus' RNA genome.  It has nothing to do with integration into host 
> DNA.  It is also the primary source of mutation in viruses that use it - 
> it has a high nucleotide misincorporation rate and no proofreading activity.
> 
But why is reverse transcriptase in the cell in the first place? What 
function does it serve in a normal, healthy cell?

I don't believe that cells make enzymes just so they can be ready to be
infected by a virus.

  Thanks,
    ++PLS