Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.27.4 (ribonuclease)
 6,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The capacity of some Escherichia coli (E. coli) ribosomal proteins to bind to tRNA and to hydrolyse their aminoacylated derivatives has been analysed. The following results were obtained: (1) The basic proteins L2, L16 and L33 and S20 bound f[3H]Met-tRNA to a similar extent as the total proteins from 30 S (TP30) or 50 S (TP50) when tested by nitrocellulose filtration, in contrast to the more acidic proteins L7/L12 and S8. (2) The proteins of the peptidyltransferase centre, L2 and L16, showed no distinct specificity, binding various charged tRNAs from E. coli and Saccharomyces cerevisiae (S. cerevisiae). (3) A number of isolated ribosomal proteins hydrolysed aminoacyl-tRNA as assessed by trichloroacetic acid precipitation, in contrast to the TP30 and TP50. (4) The loss of radiolabel from Ac[14C]Phe-tRNA and from [14C]tRNA in the presence of these proteins could not be prevented by RNasin, a ribonuclease inhibitor, whereas that mediated by a sample of non-RNase-free bovine serum albumin was inhibited. (5) When double-labelled, Ac[3H]Phe-[14C]tRNA was incubated with L2 both radiolabels were lost, indicating that this potential candidate for a peptidyltransferase enzyme does not specifically cleave the ester bond between the aminoacyl residue and the tRNA.
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PMID:The complex between ribosomal proteins and aminoacyl-tRNA: the interactions and hydrolytic activities are not confined to the proteins L2 and L16 of Escherichia coli ribosomes. 218 27

Ribosomes from 8-day-regenerating rat skeletal muscle have been shown to be more active in poly(U)-directed polyphenylalanine synthesis than ribosomes from control muscle. This difference persists after salt washing of the ribosomes and does not appear to be due to the presence of ribonuclease associated with the control ribosome population. Ribosomes from control muscle were also less active than those from regenerates in the nonenzymatic binding of phenylalanyl-tRNA to ribosomes and in the peptidyltransferase reaction. Three glutamyl-tRNA isoacceptors have been isolated from 8-day-regenerating rat skeletal muscle by preparative RPC-5 chromatography of total tRNA charged with [3H]glutamic acid. The two major isoacceptors observed, tRNAgluI and tRNAgluIII, respond to the glutamic acid codons GAG and GAA, respectively. A third, minor glutamyl isoacceptor, tRNAgluII, also responds to the codon GAA. When the three isoacceptors were tested for function in a polysomal cell-free protein synthesizing system, it was found that their relative levels of utilization were essentially identical to their relative abundances. Thus, the tRNA which increases in relative amount after the induction of regeneration, tRNAgluII, is not preferentially utilized for overall muscle protein synthesis.
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PMID:Function of ribosomes and glutamyl-tRNA isoacceptors in protein synthesis in regenerating skeletal muscle. 285 50