Figure 1.

Isolation of the human BRCA2 gene as a circular YAC using the TAR cloning method. Yeast spheroplasts were transformed with genomic human DNA along with a TAR cloning vector containing promoter (striped box) and terminal exon 27 (dotted box) sequences of BRCA2 (see Materials and Methods) at the ends of the linearized plasmid. Recombination between the sequences in the vector and BRCA2 genomic DNA led to the establishment of a circular YAC because of ARS-like sequences in the BRCA2 gene. CEN corresponds to the yeast chromosome VI centromere, and HIS3 is a selectable marker. Arrows indicate the positions of primers used for initial identification of clones containing the BRCA2 gene.