Generation of transgenic mice from yeast artificial chromosome DNA that has been modified by gene targeting

Yeast artificial chromosome (YAC) vectors permit the cloning of up to megabase fragments of human genomic DNA in yeast (Saccharomyces cerevisiae). Efficient recombination between homologous segments of DNA is one of the hallmark genetic features of yeast. This characteristic facilitates the introduction of specific mutations into YACs by gene targeting. Gene targeting has been used recently to introduce specific mutations into YACs spanning the human beta-globin locus and the human apolipoprotein (apo)-B gene, and the mutated YAC DNA has been used to generate transgenic mice. This approach has been useful for the study of the regulatory elements controlling beta-globin gene expression and for the study of apo-B structure and function. This article reviews the techniques for introducing mutations into YACs, for the purpose of expression in transgenic mice.