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At least 181 records · Page 10Linked to original sources
PubMed1980

Mechanism of codon-anticodon interaction in ribosomes. Direct functional evidence that isolated 30S subunits contain two codon-specific binding sites for transfer RNA.

30S subunits were isolated capable to bind simultaneously two molecules of Phe-tRNAPhe (or N-Acetyl-Phe-tRNAPhe), both poly(U) dependent. The site with higher affinity to tRNA was identified as P site. tRNA binding to this site was not inhibited by low concentrations of tetracycline (2 x 10(-5)M) and, on the other hand, N-Acetyl-Phe-tRNAPhe, initially prebound to the 30S.poly(U) complex in the presence of tetracycline, reacted with puromycin quantitatively after addition of 50S subunits. The site with lower affinity to tRNA revealed features of the A site: tetracycline fully inhibited the binding of both Phe-tRNAPhe and N-Acetyl-Phe-tRNAPhe. Binding of two molecules of Phe-tRNAPhe to the 30S.poly(U) complex followed by the addition of 50S subunits resulted in the formation of (Phe)2-tRNAPhe in 75-90% of the reassociated 70S ribosomes. These results prove that isolated 30S subunits contain two physically distinct centers for the binding of specific aminoacyl- (or peptidyl-) tRNA. Addition of 50S subunits results in the formation of whole 70S ribosomes with usual donor and acceptor sites.

Anticodon↗
PubMed1999

Two germline missense mutations at codons 804 and 806 of the RET proto-oncogene in the same allele in a patient with multiple endocrine neoplasia type 2B without codon 918 mutation.

Multiple endocrine neoplasia (MEN) type 2B is a clinically distinct entity among the autosomal dominant MEN 2 syndromes. Most patients with MEN 2B carry a germline mutation (M918T) of the RET proto-oncogene, while a few carry A883F. We examined a patient with MEN 2B, but without M918T or A883F, and her relatives. Here, we report the presence in this patient of 2 germline mutations, V804M and Y806C in the same allele. While the novel Y806C was inherited from her father, its carriers (her father and brother) was not affected by MEN 2. In contrast, V804M was a de novo mutation, that has been reported in patients with familial medullary thyroid carcinoma. Combinations of mutations of the RET proto-oncogene may cause oncogenic activities different from those of single mutations.

Base Sequence↗
PubMed1978

The mechanism of codon-anticodon interaction in ribosomes. Quantitative study of codon-dependent binding of tRNA to the 30-S ribosomal subunits of Escherichia coli.

The formation of a ternary complex 30-S-subunit . poly(U) . tRNAPhe is discussed and the conditions for its correct description by Langmuir's isotherm are deduced. The affinity constant of the binary complex 30-S-subunit . poly(U) is measured. The reversibility of binding of tRNAPhe to the complex 30-S-subunit . poly(U) is proved in a direct way. The main reason for the heterogeneity of ternary complexes was found to be due to the ability of high-molecular-weight poly(U) to form complicated aggregates with 30-S subunits. If a fraction of poly(U) of moderate molecular weight (30 000) is used, then the ternary complexes are homogeneous in stability and yield the same affinity constants for deacylated, aminoacylated and peptidyl-tRNAPhe (1 X 10(8) M-1 at 20 mM Mg2+, 200 mM NH+4 and 0 degrees C). Ribosomal protein S1 increases the binding constant of poly(U) with 30-S subunits but does not change the binding constant of tRNAPhe with the 30-S-subunit . poly(U) complex. All 30-S subunits, even partially stripped of S1 protein, are active in the binding of both poly(U) and tRNAPhe.

Anticodon↗
PubMedDate not supplied

[Affinity modification of 40S ribosomal subparticles from human placenta by derivatives of oligoribonucleotides, containing an AUG codon. Ribosomal proteins, forming a codon-anticodon interaction region].

Using 2',3'-O-[4-N-(2-chloroethyl)-N-methylamino]benzylydene derivatives of AUGUn [32P]pC and 4-[N-(2-chloroethyl)-N-methylamino]benzylmethylphosphoamide derivatives of [32P]pAUGUn, the affinity labelling of human placental 40S ribosomal subunits was studied within 40S initiation complexes obtained in the presence of a ternary complex eIF-2.GTP.Met-tRNA(fMet). Analysis of the ribosomal proteins labelled by these mRNA analogues revealed that proteins S3/S3a, S6, S7, and S14/S15 play a key role in the interaction of the template with the 40S subunit in the presence of the ternary complex eIF-2.GTP.Met-tRNA(fMet). Proteins S2, S4, S5, S8, S9, and S17 are also involved in this interaction.

Affinity Labels↗
PubMed1997

Characteristic distribution of bases and codons around the initiation and termination codons in whole reading frames in bacteria and yeast genomes.

Recently the complete nucleotide sequence of the entire genome was determined for yeast and a few kinds of bacterium. To see characteristic features of base sequence in the cistron (actually the open reading frame, ORF) and in the regions around a cistron (ORF), the biases of appearance frequency of bases from the base ratio were studied statistically. In the regions before the base biases were observed. The characteristic base distribution patterns were similar to all the cases of bacteria, but different from yeast. The base biases are reflected on the appearance frequency of amino acids near the N-termini and C-termini of proteins. The characteristic biases found in the amino acid sequence of the N-terminal part of bacteria proteins are different from that in yeast proteins.

Bacillus subtilis↗