"TA cloning" is a popular method of cloning without the use of restriction enzymes; instead, PCR products are amplified with only Taq DNA polymerase and other polymerases. These polymerases lack 5'-3' proofreading activity and add an adenosine triphosphate residue to the 3' ends of the double-stranded PCR products. Such PCR amplified products can thus be cloned in a linearized vector that has complementary 3' thymidine triphosphate overhangs.
The major problem is that the gene has a 50% chance of getting cloned in the reverse direction. The method also needs DNA ligase.
A recently described Quick Assemble
technique has been used to improve TA cloning. The new 2-day PCR-based method can be used to generate both circularized and linear final assembled products. The method makes the synthesis and assembly of large molecules in a quick and efficient way, while circumventing the use of DNA ligases. The new PCR-based protocol used a TA cloning vector as the template for the linear vector backbone demonstrating the ability to improve this technique.from
Zuo and Rabie in Curr. Issues Mol. Biol. 12: 11-16
Further reading: assembly of DNA fragments into circular constructs
Labels: PCR, PCR protocol