Autonomously replicating sequence

An autonomously replicating sequence (ARS or ars) contains the origin of replication in the yeast genome. The ARS of S. cerevisiae is a minimal 125 bp, and contains four regions (A, B1, B2, and B3), named in order of their effect on plasmid stability.

Source: Wikipedia — Autonomously replicating sequence (CC BY-SA 4.0)