The protein hSnm1B is stabilized when bound to the telomere-binding protein TRF2

hSnm1B is member of the SNM family of exonucleases involved in DNA processing and is known to be localized to telomeres via binding to the telomere- binding protein TRF2. Here we demonstrate that the C terminus of hSnm1B facilitates the concentration of hSnm1B on telomeres by promoting ubiquitinmediated degradation of hSnm1B that is not localized to telomeres, as well as by blocking protein degradation and fostering localization to telomeres via binding of TRF2. Finally, a mutant of hSnm1B stabilized independently of exogenous TRF2- induced cell death. Taken together, we speculate that sequestering hSnm1B at telomeres by a combination of stabilizing the protein when bound to telomeres and degrading it when not bound to telomeres may be a means to prevent potentially lethal effects of unregulated hSnm1B activity.