polyadenylation positions

[steven morse]

Hope someone out there will be able to give me some advice with
regards polyadenylation sequences.  

1)  I'm attempting to modify a vector and in the process have to
remove the polyadenylation sequence - ideally I'd like to put a
multiple cloning site before the polyadenylation sequence but will
this affect gene expression ?  

2)  One of the genes I'm interested in is CAT - does CAT require a
polyadenylation signal or is it stable enough without one ? 

3)  Is there a minimum length required between the polyA sequence and
the gene for the polyA to be effective ?

4) Is there a good review on polyA sequence structure and function ?
I did a lit. search but found very little info.

Thanks for all your help.

Stewart Martin
CRC Department of Clinical Oncology
University of Nottingham

e-mail:  stewart.martin at nott.ac.uk