THE 1ST HUMAN GENES FOR TRANSFER RNA(ICG)ARG, TRANSFER RNA(UCC)GLY, AND TRANSFER RNA(IGU)THR AND MORE TRANSFER RNA(VAL) PSEUDOGENES - EXPRESSION AND PRE-TRANSFER RNA MATURATION IN HELA CELL-FREE-EXTRACTS

A functional tRNA(Val) gene, which codes for the major tRNA(IAC)Val isoacceptor species, and three new tRNA(Val) pseudogenes have been isolated from human genomic DNA. Two tRNA(Val) pseudogenes and a tRNA(Val) variant gene were found to be associated with tRNA genes encoding tRNA(ICG)Arg, tRNA(UCC)Gly, and tRNA(IGU)Thr, respectively, on distinct DNA fragments. All tRNA genes, including the pseudogenes, are actively transcribed in HeLa nuclear extract. Pre-tRNAs of tRNA(Val), tRNA(Arg), tRNA(Thr), and tRNA(Gly) genes are correctly processed to mature-sized tRNAs, whereas the three tRNA(Val) pseudogenes yield stable pre-tRNAs in vitro. These findings reveal that, together with the three known pseudogenes, half of the members of the human tRNA(Val) gene family are pseudogenes, all of which are active in homologous nuclear extracts in vitro and presumably also in vivo.