The pYC2/CT vector contains the CEN6/ARSH4 sequence (Sikorski and Hieter, 1989) for maintenance and replication in yeast. The CEN6/ARSH4 sequence is a 518 bp hybrid DNA fragment that contains a yeast centromere sequence (CEN) and an autonomously replicating sequence (ARS) (Sikorski and Hieter, 1989). The CEN6 sequence is derived from the CEN6 locus of yeast chromosome 6 (Panzeri and Philippsen, 1982) while the ARSH4 sequence is derived from the yeast histone H4-associated ARS (Bouton and Smith, 1986). When placed in a heterologous expression plasmid (i.e. pYC2/CT), the presence of the CEN6/ARSH4 sequence allows non-integrative centromeric maintenance and low copy number replication of the plasmid (generally 1–2 copies per cell).