Abstract
Multiple functions of methyl-deficient tRNA m et, including those specific for initiator tRNA, were investigated and compared with normal tRNA m et. A comparison of the chromatographic properties of normal and methyl-deficient methionyl-tRNA showed identical elution profiles on methylated albumin-Kieselguhr, benzoylated o-(diethylaminoethyl)cellulose, and reverse phase chromatography (isoamylacetate) columns, but resolved a unique peak of methyl-deficient methionyl-tRNA on a reverse phase chromatography (Freon) column. We were unable to recover active pure methyl-deficient tRNA from this column, so that most subsequent studies had to be done on unfractionated methyl-deficient tRNA preparations. The only abnormality noted for methyl-deficient tRNA m et was a low velocity of acylation for the unique methyl-deficient peak. This was exhibited by examining the different patterns obtained on reverse phase chromatography for partially acylated compared to fully acylated tRNA m et. In all other ways tested the methyl-deficient tRNA m et functioned normally. Coding with AUG and GUG triplets was indistinguishable from normal as was the stimulation of this binding by purified initiation factors. Extent and rate of formylation, exclusion from recognition by bacterial elongation factors and function in NH2-terminal dipeptide synthesis all appeared to be normal in the methyl-deficient tRNA. Of peripheral interest was the finding that tRNA m etm appears to be acylated about 2.2 times more rapidly by purified methionyl-tRNA synthetase than tRNA m etf.
Highlights
Because of its unique role in protein synthesis, tRNAyet has a number of highly specific functions characteristic of only this species of tRNA
We thought that methylation might play a role in any one of these functions as well as in coding or aminoacylation properties of tRNAMet
Activity-A problem unique to investigation of biological properties of methyl-deficient tRNAMet is that any crude enzyme preparation used to acylate the tRNA may contain methylating activity which, in the presence of methionine, might methylate the methyl-deficient species
Summary
Multiple functions of methyl-deficient tRNAMet, including those specific for initiator tRNA, were investigated and compared with normal tRNAMet. Because of its unique role in protein synthesis, tRNAyet has a number of highly specific functions characteristic of only this species of tRNA. These include the transformylation reaction [11, 12], codon recognition of GUG and AUG triplets, recognition by the bacterial initiation factors [13], and exclusion of recognition by elongation factors [14]. We thought that methylation might play a role in any one of these functions as well as in coding or aminoacylation properties of tRNAMet. An examination was made of all of these functions of methyl-deficient tRNAMet. In this paper we report the results of these studies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
