Component of the origin recognition complex (ORC) that binds origins of replication. It has a role in both chromosomal replication and mating type transcriptional silencing. ORC binds to multiple sites within the ars1 origin of DNA replication in an ATP-independent manner. ORC is composed of six subunits. ORC interacts with cdc18, recruiting it to the ars1 origin of replication (PubMed:10535928, PubMed:11850415). Interacts with sbp70 (PubMed:15314153). Expressed constitutively during the cell cycle. Belongs to the ORC1 family.