Catalyzes the 2-oxoglutarate and iron-dependent C4-lysyl hydroxylation of ETF1 at 'Lys-63' thereby promoting the translational termination efficiency of ETF1 (By similarity). Not essential for embryonic stem cell (ESC) maintenance and the embryonic and postnatal development (PubMed:27147518). 2-oxoglutarate + L-lysyl-[protein] + O2 = 4-hydroxy-L-lysyl-[protein] + CO2 + succinate Interacts with ETF1 (By similarity). Interacts with the ETF1-GSPT1 complex (By similarity). Mice are born at the expected Mendelian rate and are healthy, fertile and physiologically normal (PubMed:27147518). Embryonic stem cells (ESCs) exhibit normal colony morphology and cell proliferation rates and maintain normal expression of pluripotent genes (PubMed:27147518).