IDENTIFICATION OF THE TRANSFER-RNAS WHICH UP-REGULATE AGROSTIN, BARLEY RIP AND PAP-S, 3 RIBOSOME-INACTIVATING PROTEINS OF PLANT-ORIGIN

Ribosome-inactivating proteins (RIP) are RNA-N-glycosidases widely dif fused in plants which depurinate ribosomal RNA at a specific universal ly conserved position, A4324 in rat ribosomes, A small group of RIPs ( cofactor-dependent RIPs) require ATP and tRNA to reach maximal activit y on isolated ribosomes, The tRNA which stimulates gelonin was identif ied as tRNA(Trp). The present paper reports the identification of thre e other tRNAs which stimulate agrostin (tRNA(Ala)), barley RIP (tRNA(A la), tRNA(Val)) and PAP-S (tRNA(Gly)), while for tritin-S no particula r stimulating tRNA emerged. The sequences of tRNA(Val) and tRNA(Gly) c orrespond to the already known ones (rabbit and man, respectively). Th e tRNA(Ala) (anticodon IGC) identifies a new isoacceptor, Only the sti mulating activity of the tRN(Ala) for agrostin approaches the specific ity previously observed for the couple gelonin-tRNA(Trp). (C) 1998 Fed eration of European Biochemical Societies.