Origin recognition complex subunit 3 (Orc3) is a subunit of the heterohexameric origin recognition complex (ORC) that is essential for coordinating replication onset. ORC binds to the origin of replication, binds CDC6, and recruits the hexameric MCM2-7 ring to the DNA, which leads to the assembly of the pre-replicative complex (pre-RC). Five of the 6 ORC subunits (Orc 1-5) retain AAA+ (ATPases associated with a variety of cellular activities) folds, but Orc3, as well as Orc2, lost their ATP-binding signatures.
Jiyao W et al.(2023). "The conserved domain database in 2023.",