Recent studies demonstrate that UHRF1 is required for DNA methylation 
maintenance by targeting DNMT1 to DNA replication foci, presumably through its 
unique hemi-methylated DNA-binding activity and interaction with DNMT1. UHRF2, 
another member of the UHRF family proteins, is highly similar to UHRF1 in both 
sequence and structure, raising questions about its role in DNA methylation. In 
this study, we demonstrate that, like UHRF1, UHRF2 also binds preferentially to 
methylated histone H3 lysine 9 (H3K9) through its conserved tudor domain and 
hemi-methylated DNA through the SET and Ring associated domain. Like UHRF1, 
UHRF2 is enriched in pericentric heterochromatin. The heterochromatin 
localization depends to large extent on its methylated H3K9-binding activity and 
to less extent on its methylated DNA-binding activity. Coimmunoprecipitation 
experiments demonstrate that both UHRF1 and UHRF2 interact with DNMT1, DNMT3a, 
DNMT3b and G9a. Despite all these conserved functions, we find that UHRF2 is not 
able to rescue the DNA methylation defect in Uhrf1 null mouse embryonic stem 
cells. This can be attributed to the inability for UHRF2 to recruit DNMT1 to 
replication foci during S phase of the cell cycle. Indeed, we find that while 
UHRF1 interacts with DNMT1 in an S phase-dependent manner in cells, UHRF2 does 
not. Thus, our study demonstrates that UHRF2 and UHRF1 are not functionally 
redundant in DNA methylation maintenance and reveals the cell-cycle-dependent 
interaction between UHRF1 and DNMT1 as a key regulatory mechanism targeting 
DNMT1 for DNA methylation.