Effect of chromosomal position on amplification of transfected genes in animal cells.

A single protein (CAD) contains the first three enzymatic activities of de novo uridine biosynthesis. The chromosomal location of CAD genes introduced into Chinese hamster ovary cells significantly affects the frequency and cytogenetic result of their amplification. The amplification frequency in one transformant is 100-fold that of the others; in another, amplification of donated genes inserted near a centromere results in chromosome instability and rearrangements.