Yeast Artificial Chromosome

A YAC (Yeast Artificial Chromosome ) is an artificial chromosome, which is modeled on the chromosomes of yeast.

Properties

It serves as a vector, and allows, in contrast to cosmid cloning of large genome segments. The first YAC was created as a combination of an ARS and a centromere of yeast with the telomeres of Tetrahymena, which was a linear molecule that behaves in a yeast as a normal chromosome. The first YAC was developed by Murray and Szostak 1983.

Despite this advantage, the YACs have one major drawback. Due to its length, it is very difficult to handle in liquid medium and to keep intact. For this reason, an attempt was made previously, the sections no longer than 50 to 100 kbp to construct. By fractionation by pulsed field gel electrophoresis, short DNA fragments were removed from the molecule, and the average length was extended to 350 kbp. By the use of polyamines to stabilize the molecules has been achieved, which is used in the human and the mouse genome insertions of up to 700 kbp were possible. 1992, a gene library with an average of 810 kbp was Insertionsgrößen developed, some molecules reach lengths of up to 1800 kbp.

As alternatives to the YACs were now both BACs and PACs, eventually even MACs (big MACs) and Human Artificial Chromosomess developed.