A rapid isolation of the unknown 5'-flanking sequence of human CENP-B cDNA with polymerase chain reactions.

We rapidly and efficiently isolated the 5'-region of cDNA encoding the N-terminal region of human centromere antigen B (CENP-B) including an ATG methionine codon by polymerase chain reactions (PCR). The unknown 5'-flanking sequence of the cDNA was amplified using an adaptor-sequence ligated to the 5' end as a universal primer sequence. To locate the target fragments, we did an additional PCR with another set of two internal primers using samples of the size-fractionated products as templates, rather than using the conventional hybridization procedure. This approach can further be applied to the analysis of other unknown flanking sequences of cDNA or genomic DNA.