In order to identify the molecular mechanism leading to the increase of TRMT6/61A complex in aged HSCs, we purified proteins interacting with TRMT6 and TRMT61A via affinity purification. HEK293T cells stably expressing SFB-tagged TRMT6 or SFB-TRMT61A were lysed in NETN buffer (20 mM Tris-HCl [pH 8.0], 100 mM NaCl, 1 mM EDTA, and 0.5% Non- idet P-40, containing protease and phosphatase inhibitors cocktail) on ice for 30 min. Cell debris were removed by centrifugation and the supernatant were collected and incubated with 50 μL S-protein beads for 4 hr at 4 ℃. Beads were washed with 1 mL NTEN buffer for three times, the immunocomplexes were boiled in 20 μL 2 x SDS loading buffer. Samples were resolved on 10% SDS-PAGE and analyzed by mass spectrometry.