Where to place the polyA signal? - (Dec/28/2012 )

Hello everyone,
I have a few of questions

1)How far off can a polyA signal be placed after the stop codon; i.e what is the optimal range, very close or far off?

2)How far off after the polyA signal can one place a new MCS?

3)Are there major specific differences between bGH or SV40 polya signals regarding different proteins? and which ones are preferred to be placed after something like puromycin?

If you know any good read regarding this topic please let me know.


Thanks!

in our virus poly A is around 10 to 25 b after the stop codon. the new MCS is around 30 to 150 b after poly A. it depends on the genes. question 3 I'm not sure.