One-Step Bacterial Artificial Chromosome (BAC) Modification: Preparation of the A Homology Arm (A-Box).

The one-step approach to bacterial artificial chromosome (BAC) modification requires that only one homology arm be cloned into the shuttle vector (in the example presented here, we use the "A-box"). The homology arm, which in this case lies upstream of the ATG start codon, is amplified by polymerase chain reaction (PCR) using purified BAC DNA as template. The resulting amplification product is then digested with the appropriate restriction endonuclease to render it suitable for cloning into the shuttle vector.