ORC3

The origin recognition complex (ORC) is a highly conserved six subunits protein complex essential for the initiation of the DNA replication in eukaryotic cells. Studies in yeast demonstrated that ORC binds specifically to origins of replication and serves as a platform for the assembly of additional initiation factors such as Cdc6 and Mcm proteins. The protein encoded by this gene is a subunit of the ORC complex. Studies of a similar gene in Drosophila suggested a possible role of this protein in neuronal proliferation and olfactory memory. Alternatively spliced transcript variants encoding distinct isoforms have been reported for this gene.

Full Name

Origin Recognition Complex Subunit 3

Function

Component of the origin recognition complex (ORC) that binds origins of replication. DNA-binding is ATP-dependent. The specific DNA sequences that define origins of replication have not been identified yet. ORC is required to assemble the pre-replication complex necessary to initiate DNA replication. Binds histone H3 and H4 trimethylation marks H3K9me3, H3K27me3 and H4K20me3.

Cellular Location

Nucleus
Chromosome

PTM

Multi-mono-ubiquitinated by OBI1; ubiquitination is important for efficient DNA replication origin site activation. Ubiquitination levels are low in mitotic and early G1-phAse cells and are induced in late G1-/early S-phase, peaking in S-phase and decrease toward the end of the cell cycle.