P1-derived artificial chromosome
A P1 artificial chromosome (PAC ) (also -derived P1 or P1 -based) is an artificial chromosome that was developed from the P1 vector of the temperate bacteriophage P1. In contrast to the artificial chromosomes cosmids allow cloning of large genome segments. PAC is used as a vector and is more stable as the YAC.
The first PAC was developed by Ioannou (see references ) by a combination of the P1 vector and the Q -factor system and can be used for insertions of kbp genome segments with lengths between 100 and 300.