Unmethylated CpG islands (CGIs)-binding protein which localizes to H3K4me3-decorated CGIs, where it acts as a transcriptional repressor (PubMed:33980486). Tethers L3MBTL3 to chromatin and interacts with the KDM1A histone demethylase complex to modulate H3K4me2 and H3K4me3 levels at CGIs (PubMed:33980486). Plays a role in atherogenesis by binding with LDL on cell surface and promoting LDL oxidation which leads to the formation of foam cell (PubMed:16159594, PubMed:34006929).