Biochemistry, Biophysics, and Structural Biology Commons^™

Modulation Of Queuine Uptake In Cultured Human Fibroblasts By Phorbol Esters And Interferons, Debra L. Crane

Chemistry & Biochemistry Theses & Dissertations

Queuosine, a nucleoside found exclusively in the first position of the anticodon of transfer RNA (tRNA), is generated post-transcriptionally in an exchange of guanine for queuine by the modifying enzyme tRNA-guanine ribosyltransferase. Phorbol ester tumor promoters were shown to induce queuine hypomodified tRNA, and that phorbol ester action was due, in part, to inhibition of queuine transport across the cell membrane. An unidentified protein designated conditioned medium factor (CMF) that potentiated a phorbol-induced inhibition of queuine uptake was also documented. We suggest here that phorbol ester-induced inhibition of queuine uptake is not a significant factor in inducing queuine-deficient tRNA although …