Characterization of the mechanism of cellular and cell free protein synthesis inhibition by an anti-tumor ribonuclease.
Onconase, a protein with anti-tumor activity, causes potent inhibition of protein synthesis in the rabbit reticulocyte lysate (IC50 10(-11) M) and when microinjected into Xenopus oocytes (IC50 10(-10) M). Onconase is a member of the RNase A superfamily; however, unlike RNase A, the mechanism of protein synthesis inhibition does not involve apparent degradation of lysate or cellular ribosomal RNAs. Rather, reticulocyte and oocyte tRNA is hydrolyzed after Onconase treatment. Furthermore, re-addition of tRNA to Onconase pretreated lysates or oocytes restores the translational capacity of the system. Taken together these results suggest that Onconase causes potent protein synthesis inhibition by a mechanism involving inactivation of cellular tRNA.
Lin
J J
JJ
Laboratory of Biochemical Physiology, NCI-FCRDC, NIH, MD 21702-1201.
Newton
D L
DL
Mikulski
S M
SM
Kung
H F
HF
Youle
R J
RJ
Rybak
S M
SM
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001345:Autoradiography; D002474:Cell-Free System; D004527:Egg Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D008845:Microinjections; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D012337:RNA, Ribosomal, 18S / Q000302:isolation & purification / Q000378:metabolism; D012339:RNA, Ribosomal, 28S / Q000302:isolation & purification / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000187:drug effects / Q000378:metabolism*; D012260:Ribonucleases / Q000008:administration & dosage / Q000494:pharmacology*; D013462:Sulfur Radioisotopes; D014981:Xenopus
D000970:Antineoplastic Agents; D004527:Egg Proteins; D011500:Protein Synthesis Inhibitors; D012337:RNA, Ribosomal, 18S; D012339:RNA, Ribosomal, 28S; D013462:Sulfur Radioisotopes; D008715:Methionine; D012260:Ribonucleases; C058703:ranpirnase