Queuine salvage in mammalian cells. Evidence that queuine is generated from queuosine 5'-phosphate

Cell-free extracts of the Vero cell line (monkey kidney origin) contain an activity which converts 7-[5-[( (1S,4S,5R)-4, 5-dihydroxy-2-cyclopenten-1-yl)-amino]methyl]-7-deazaguanosine (queuosine) 5'-phosphate into queuine (the base of queuosine). We designate this the queuine salvage activity because it apparently is responsible for the ability of intact Vero cells to salvage queuosine base from tRNA degraded during the normal turnover process. Queuosine-3'-P, mannosylqueuosine-5'-P, or queuosine nucleoside does not support the queuine salvage reaction. Extracts of the L-M cell line (mouse embryo origin) lack the queuine salvage activity, a finding consistent with the inability of intact L-M cells to retrieve queuine subsequent to tRNA turnover (Gündüz, U., and Katze, J. R. (1982) Biochem. Biophys. Res. Commun. 109, 159-167).