T/A cloning: efficient enough for library-making?

Peter Wang plw at mrc-lmb.cam.ac.uk
Tue Oct 15 20:06:27 EST 1996

Question to those of you that know a lot about T/A cloning (which is 
often used to clone PCR products - taking advantage of the single 
untemplated A's that are added by Taq polymerase, these are ligated to a 
vector that has complementary single T overhangs):

How efficient is it?  Not just does it give a high percentage of clones 
with inserts, but is the absolute number of clones with inserts as high 
as you would get with sticky-end or blunt-end ligations?

I wonder about T/A ligation efficiency because several times in the New 
England Biolabs catalog it is said that fragments generated by 
restriction enzymes leaving a single base overhang are difficult to 

I was thinking about using a T/A cloning strategy to shotgun clone a 
library of quite small DNA fragments, and would like to avoid the use of 

Thanks in advance for any insights or suggestions; please email direct 
as well as posting, if you don't mind.
Peter Wang, M.D., Ph.D.
MRC Centre for Protein Engineering,
Hills Road, Cambridge, CB2 2QH, England

Tel (01223) 402104  (international calls +44-1223-402104)
Fax (01223) 402140  (     "          "   +44-1223-402140)

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