vector dephosphorylation - (Oct/11/2012 )

I've doube digested my pCMV5 vector with EcoRI an BglII, and as I've got some problem with it self-ligating, i've dephosphorylated it with CIAP. Now, do I need my ligase buffer to be free of ATP?? ( the insert is still phosphorylated after the same double digestion)

you can try ligating it directly.
Why r u asking "Now, do I need my ligase buffer to be free of ATP??"

because as the CIAP is not heat inactivated i have to clean-up the reaction, and resuspend it in a ligase buffer (containg ATP); i'm asking whether the ligase with atp won't rephosphorylase the vector making it capable to self ligate once more

T4 polynucleotide kinase need to be present in reaction to make vector rephosphorylated. your ligase reaction do not have it. so no need to worry abt ATP.

thx very much!!

You should switch to shrimp alkaline phosphatase or antarctic phosphatase, both of which can be heat killed, avoiding a painful cleanup step. The less you do to your DNA, the fewer opportunities for problems.