Human TP53 from the malignant glioma-derived cell lines M059J and M059K has a cancer-associated mutation in exon 8

The protein coding segment of the TP53 genes from the glioma-derived cell lines M059J and M059K was sequenced. The sequences from both cell lines were identical over 5039 bp, including the gene segment containing exons 2 through 9, exon 10, and the proximal segment of exon 11. In both cells, the first nucleotide of codon 286 (GAA, Glu) is changed to an A (AAA, Lys). Comparison with the same TP53 segment from the A549 human lung carcinoma cell line revealed several differences in intron sequence.     

Intragenic suppression in the uvrD gene of Escherichia coli. I. Temperature-sensitive uvrD mutations

A temperature-sensitive uvrD mutant, HD323 uvrD4, was isolated from the uvrD mutant HD4 uvrD3. The temperature sensitivity of the uvrD4 gene product was reversible. The suppressor mutation uvrD44 which rendered the uvrD3 mutant temperature-sensitive could be separated from the uvrD3 mutation by replacing the PstI fragment, which encodes the C-terminal half of the UvrD protein. The uvrD44 mutation was found to make host bacteria lethal at non-permissive temperatures only when cloned on a low copy vector pMF3. The nucleotide sequence of the uvrD3 and uvrD4 mutant genes was determined. The nucleotide change found in the uvrD3 at +1235, GAA to AAA, only alters the amino acid sequence from Glu at 387 to Lys. The uvrD44 has another nucleotide change at +1859, GAA to AAA (Glu at 595 to Lys), which is considered to be the suppressor mutation uvrD44.     

家蚕磷酸吡哆醇氧化酶的体外定点突变及其活性鉴定

[目的]研究家蚕Bombyx mori磷酸吡哆醇氧化酶(pyridoxine 5’-phosphate oxidase,PNPO)个别保守氨基酸残基对PNPO酶活性的影响.[方法]用重叠延伸法把氨基酸残基Lys111 (AAA)突变为Glu (GAA),Ser160(AGC)定点突变为Ala(GCC);构建重组表达载体...     

Selenium-containing tRNA(Glu) and tRNA(Lys) from Escherichia coli: purification, codon specificity and translational activity

In response to low (approximately 1 microM) levels of selenium, Escherichia coli synthesizes tRNA(Glu) and tRNA(Lys) species that contain 5-methylaminomethyl-2-selenouridine (mnm5Se2U) instead of 5-methylaminomethyl-2-thiouridine (mnm5S2U). Purified glutamate- and lysine-accepting tRNAs containing either mnm5Se2U (tRNA(SeGlu), tRNA(SeLys] or mnm5S2U (tRNA(SGlu), tRNA(SLys] were prepared by RPC-5 reversed-phase chromatography, affinity chromatography using anti-AMP antibodies and DEAE-5PW ion-exchange HPLC. Since mnm5Se2U, like mnm5S2U, appears to occupy the wobble position of the anticodon, the recognition of glutamate codons (GAA and GAG) and lysine codons (AAA and AAG) was studied. While tRNA(SGlu) greatly preferred GAA over GAG, tRNA(SeGlu) showed less preference. Similarly, tRNA(SGlu) preferred AAA over AAG, while tRNA(SeLys) did not. In a wheat germ extract--rabbit globin mRNA translation system, incorporation of lysine and glutamate into protein was generally greater when added as aminoacylated tRNA(Se) than as aminoacylated tRNA(S). In globin mRNA the glutamate and lysine codons GAG and AAG are more numerous than GAA and AAA, thus a more efficient translation of globin message with tRNA(Se) might be expected because of facilitated recognition of codons ending in G.     

Identification of a single base-pair mutation of TAA (Stop codon) → GAA (Glu) that causes light chain extension in a CHO cell derived IgG1

We describe here the identification of a stop codon TAA (Stop) → GAA (Glu) = Stop221E mutation on the light chain of a recombinant IgG1 antibody expressed in a Chinese hamster ovary (CHO) cell line. The extended light chain variants, which were caused by translation beyond the mutated stop codon to the next alternative in-frame stop codon, were observed by mass spectra analysis. The abnormal peptide peaks present in tryptic and chymotryptic LC–MS peptide mapping were confirmed by N-terminal sequencing as C-terminal light chain extension peptides. Furthermore, LC-MS/MS of Glu-C peptide mapping confirmed the stop221E mutation, which is consistent with a single base-pair mutation in TAA (stop codon) to GAA (Glu). The light chain variants were approximately 13.6% of wild type light chain as estimated by RP-HPLC analysis. DNA sequencing techniques determined a single base pair stop codon mutation, instead of a stop codon read-through, as the cause of this light chain extension. To our knowledge, the stop codon mutation has not been reported for IgGs expressed in CHO cells. These results demonstrate orthogonal techniques should be implemented to characterize recombinant proteins and select appropriate cell lines for production of therapeutic proteins because modifications could occur at unexpected locations.     

Identification of a single base-pair mutation of TAA (Stop codon) → GAA (Glu) that causes light chain extension in a CHO cell derived IgG1

We describe here the identification of a stop codon TAA (Stop) → GAA (Glu) = Stop221E mutation on the light chain of a recombinant IgG1 antibody expressed in a Chinese hamster ovary (CHO) cell line. The extended light chain variants, which were caused by translation beyond the mutated stop codon to the next alternative in-frame stop codon, were observed by mass spectra analysis. The abnormal peptide peaks present in tryptic and chymotryptic LC–MS peptide mapping were confirmed by N-terminal sequencing as C-terminal light chain extension peptides. Furthermore, LC-MS/MS of Glu-C peptide mapping confirmed the stop221E mutation, which is consistent with a single base-pair mutation in TAA (stop codon) to GAA (Glu). The light chain variants were approximately 13.6% of wild type light chain as estimated by RP-HPLC analysis. DNA sequencing techniques determined a single base pair stop codon mutation, instead of a stop codon read-through, as the cause of this light chain extension. To our knowledge, the stop codon mutation has not been reported for IgGs expressed in CHO cells. These results demonstrate orthogonal techniques should be implemented to characterize recombinant proteins and select appropriate cell lines for production of therapeutic proteins because modifications could occur at unexpected locations.     

Distinct missense mutations of the FGFR3 lys650 codon modulate receptor kinase activation and the severity of the skeletal dysplasia phenotype

The fibroblast growth factor-receptor 3 (FGFR3) Lys650 codon is located within a critical region of the tyrosine kinase-domain activation loop. Two missense mutations in this codon are known to result in strong constitutive activation of the FGFR3 tyrosine kinase and cause three different skeletal dysplasia syndromes-thanatophoric dysplasia type II (TD2) (A1948G [Lys650Glu]) and SADDAN (severe achondroplasia with developmental delay and acanthosis nigricans) syndrome and thanatophoric dysplasia type I (TD1) (both due to A1949T [Lys650Met]). Other mutations within the FGFR3 tyrosine kinase domain (e.g., C1620A or C1620G [both resulting in Asn540Lys]) are known to cause hypochondroplasia, a relatively common but milder skeletal dysplasia. In 90 individuals with suspected clinical diagnoses of hypochondroplasia who do not have Asn540Lys mutations, we screened for mutations, in FGFR3 exon 15, that would disrupt a unique BbsI restriction site that includes the Lys650 codon. We report here the discovery of three novel mutations (G1950T and G1950C [both resulting in Lys650Asn] and A1948C [Lys650Gln]) occurring in six individuals from five families. Several physical and radiological features of these individuals were significantly milder than those in individuals with the Asn540Lys mutations. The Lys650Asn/Gln mutations result in constitutive activation of the FGFR3 tyrosine kinase but to a lesser degree than that observed with the Lys540Glu and Lys650Met mutations. These results demonstrate that different amino acid substitutions at the FGFR3 Lys650 codon can result in several different skeletal dysplasia phenotypes.     

Association between Glu504Lys Polymorphism of ALDH2 Gene and Cancer Risk: A Meta-Analysis

BackgroundThe association of the aldehyde dehydrogenases-2 (ALDH2) Glu504Lys polymorphism (also named Glu487Lys, or rs671) and cancers has been investigated. This meta-analysis aims to comprehensively assess the influence of this polymorphism on the overall cancer risk.MethodsEligible publications were retrieved according to inclusion/exclusion criteria and the data were analyzed using the Review Manager software (V5.2).ResultsA meta-analysis based on 51 case-control studies consisting of 16774 cases and 32060 controls was performed to evaluate the association between the ALDH2 Glu504Lys polymorphism and cancer risk. The comparison of genotypes Lys+ (Lys/Lys and Lys/Glu) with Glu/Glu yielded a significant 20% increased cancer risk (OR = 1.20, 95%CI: 1.03–1.39, P = 0.02, I² = 92%). Subgroup analysis by cancer type indicated a significantly increased UADT cancer risk (OR = 1.39, 95%CI: 1.11–1.73, P = 0.004, I² = 94%) in individuals with the Lys+ genotypes. Subgroup analysis by country indicated that individuals from Japan with the Lys+ genotypes had a significant 38% increased cancer risk (OR = 1.38, 95%CI: 1.12–1.71, P = 0.003, I² = 93%).ConclusionsOur results indicated that the ALDH2 Glu504Lys polymorphism is a susceptible loci associated with overall cancers, especially esophageal cancer and among Japanese population.     

Characterisation of the alpha-1-antitrypsin M3 gene,a normal variant

Summary By sequence analysis of the complete proteincoding region of the human alpha-1-antitrypsin gene using polymerase chain reaction techniques, we have characterised one of the normal variants, M3. We have identified a single point mutation between M1 Va1²¹³ and M3 at codon position 376 which is a GAA(Glu) to GAC(Asp) transversion.     

杨树派间不同种的遗传密码子使用频率分析

遗传密码子的简并性特征造成了不同物种使用的密码子存在偏爱性。了解不同物种的密码子使用特点,可以为外源基因导入过程中的基因改造提供依据,从而实现外源基因的高效表达。杨树是世界上广泛栽培的重要造林树种之一,已经成为林木基因工程研究的模式植物。本研究采用高频密码子分析法,对美洲山杨P.tremuloides,毛白杨P.tomentosa,美洲黑杨P.deltoids和毛果杨P.trichocarpa 4种杨树的蛋白质编码基因序列(CDS)进行了分析,计算出了杨树同义密码子相对使用频率(RFSC),确定了4种杨树的高频率密码子,发现虽然不同种类的杨树密码子使用上有一些差别,但是偏爱密码子的差别却很小,共性的密码子占绝大多数。仅有Pro,Thr和Cys等少数几个氨基酸的偏爱密码子有差别。这种“共性”提示我们,用不同种的杨树中任何一种杨树的偏爱密码子所设计的外源基因在其他杨树中也可以使用。     

Codon reading and translational error. Reading of the glutamine and lysine codons during protein synthesis in vitro

The reading of glutamine and lysine codons during protein synthesis in vitro has been investigated using an MS2-RNA-programed system derived from Escherichia coli. Under conditions when either glutaminyl-tRNA1Gln (s2UUG) or glutaminyl-tRNA2Gln (CUG) was the only source of glutamine for protein synthesis both tRNAs were able to read the glutamine codons CAA and CAG as indicated by the incorporation of labeled glutamine into the pertinent coat protein tryptic peptides. On the other hand, when the two glutamine tRNAs competed for the codon CAA the reading efficiency of the anticodon s2UUG, which reads the codon according to the wobble rules, was almost 40 times higher than that of the competing anticodon CUG, which reads the codon by "two out of three," i.e. it cannot form a regular base pair with the third codon position. In reading the codon CAG the anticodon CUG was approximately eight times more efficient than the anticodon s2UUG. The lysyl-tRNA1Lys (CUU) could not alone sustain any detectable coat protein synthesis in the MS2 system indicating that there was no significant reading of the lysine codon AAA. This conclusion is supported by the outcome of experiments where lysyl-tRNA1Lys (CUU) and lysyl-tRNA2Lys (s2UUU) competed for the codon AAA. The reading efficiency of the anticodon CUU was less than 1% of that of the competing s2UUU which represents the limit of resolution of our experimental system. When the two lysine tRNAs competed for the codon AAG the anticodon CUU was about four times more efficient than s2UUU. These results are discussed in the context of the two out of three hypothesis, which attempts to relate the frequency of such reading to the hydrogen bonding properties of the codon nucleotides.     

A novel skeletal dysplasia with developmental delay and acanthosis nigricans is caused by a Lys650Met mutation in the fibroblast growth factor receptor 3 gene

We have identified a novel fibroblast growth factor receptor 3 (FGFR3) missense mutation in four unrelated individuals with skeletal dysplasia that approaches the severity observed in thanatophoric dysplasia type I (TD1). However, three of the four individuals developed extensive areas of acanthosis nigricans beginning in early childhood, suffer from severe neurological impairments, and have survived past infancy without prolonged life-support measures. The FGFR3 mutation (A1949T: Lys650Met) occurs at the nucleotide adjacent to the TD type II (TD2) mutation (A1948G: Lys650Glu) and results in a different amino acid substitution at a highly conserved codon in the kinase domain activation loop. Transient transfection studies with FGFR3 mutant constructs show that the Lys650Met mutation causes a dramatic increase in constitutive receptor kinase activity, approximately three times greater than that observed with the Lys650Glu mutation. We refer to the phenotype caused by the Lys650Met mutation as "severe achondroplasia with developmental delay and acanthosis nigricans" (SADDAN) because it differs significantly from the phenotypes of other known FGFR3 mutations.     

Importance of conserved N-domain residues Thr441, Glu442, Lys515, Arg560, and Leu562 of sarcoplasmic reticulum Ca2+-ATPase for MgATP binding and subsequent catalytic steps. Plasticity of the nucleotide-binding site

Nine single mutations were introduced to amino acid residues Thr441, Glu442, Lys515, Arg560, Cys561, and Leu562 located in the nucleotide-binding domain of sarcoplasmic reticulum Ca2+-ATPase, and the functional consequences were studied in a direct nucleotide binding assay, as well as by steady-state and transient kinetic measurements of the overall and partial reactions of the transport cycle. Some partial reaction steps were also examined in mutants with alterations to Phe487, Arg489, and Lys492. The results implicate all these residues, except Cys561, in high affinity nucleotide binding at the substrate site. Mutations Thr441 --> Ala, Glu442 --> Ala, and Leu562 --> Phe were more detrimental to MgATP binding than to ATP binding, thus pointing to a role for these residues in the binding of Mg2+ or to a difference between the interactions with MgATP and ATP. Subsequent catalytic steps were also selectively affected by the mutations, showing the involvement of the nucleotide-binding domain in these reactions. Mutation of Arg560 inhibited phosphoryl transfer but enhanced the E1PCa2 --> E2P conformational transition, whereas mutations Thr441 --> Ala, Glu442 --> Ala, Lys492 --> Leu, and Lys515 --> Ala inhibited the E1PCa2 --> E2P transition. Hydrolysis of the E2P phosphoenzyme intermediate was enhanced in Glu442 --> Ala, Lys492 --> Leu, Lys515 --> Ala, and Arg560 --> Glu. None of the mutations affected the low affinity activation by nucleotide of the phosphoenzyme-processing steps, indicating that modulatory nucleotide interacts differently from substrate nucleotide. Mutation Glu442 --> Ala greatly enhanced reaction of Lys515 with fluorescein isothiocyanate, indicating that the two residues form a salt link in the native protein.     

Prediction of gene expression under drought stress in spring wheat using codon usage pattern

Spring wheat (Triticum aestivum) is a staple food providing sources of essential proteins for human. In fact, gene expressions of wheat play an important role in growth and productivity that are affected by drought stress. The objective of this work focused on analysis gene feature on spring wheat represented by nucleotide and gene expressions under drought stress. It was found that the higher codon adaptation index was in both wheat root and L-galactono-1, 4-lactone dehydrogenase. It was also found that guanine and cytosine content were high (55.56%) in wheat root. Whereas, guanine and cytosine content were low (41.28%) in L-galactono-1, 4-lactone dehydrogenase. Moreover, the higher relative synonymous codon usage value was observed in codon CAA (1.20), GAA (1.33), GAT (1.00), and ATG (1.00) in wheat root and thus about 62.95% of the total variation in relative synonymous codon was explained by principal component analysis. Additionally, high averages frequency number of codon were (above 15.76) in Met, Lys, Ala, Gly, Phe, Asp, Glu, His, and Tyr; whereas, low averages were in remaining amino acids and majority (90%) of modified relative codon bias values was between 0.40 and 0.90. Shortly, calculations and analysis of codon usage pattern under drought stress would help for genetic engineering, molecular evolution, and gene prediction in wheat studies for developing varieties that associate with drought tolerance.     

Alcohol and aldehyde dehydrogenase polymorphisms and risk for suicide: a preliminary observation in the Japanese male population

Epidemiological studies have shown that excessive alcohol consumption is a potent risk factor to develop suicidal behavior. Genetic factors for suicidal behavior have been observed in family, twin, and adoption studies. Because alcohol dehydrogenase (ADH1B) His47Arg and mitochondrial aldehyde dehydrogenase (ALDH2) Glu487Lys single nucleotide polymorphisms (SNPs), which affect alcohol metabolism, have been reported to exert significant impacts on alcohol consumption and on the risk for alcoholism in East Asia populations, we explored associations of the two functional SNPs with suicide using a case–control study of 283 completed suicides and 319 control subjects in the Japanese population. We found that the inactive ALDH2 allele (487Lys) was significantly less frequent in the completed suicides (19.3%) than in the controls (29.3%), especially in males, whereas this was not the case in females. The males bearing alcoholism‐susceptible homozygotes at both loci (inactive ADH1B Arg/Arg and active ALDH2 Glu/Glu genotypes) have a 10 times greater risk for suicide compared with the males bearing alcoholism‐protective homozygotes at both loci. Our data show the genetic impact of the two polymorphisms on suicidal behavior in the Japanese population, especially in males. Because we did not verify the daily alcohol consumption, the association of these SNPs with suicide might be due to alcoholism itself. Further studies using case–control subjects, which verifies the details of current and past alcohol consumption and diagnosis for alcoholism, are required to confirm these findings.     

Mitochondrial gene diversity associated with the atp9 stop codon in natural populations of wild carrot (Daucus carota ssp. carota)

Mitochondrial genomes extracted from the wild populations of Daucus carota have been used as a genetic resource by breeders of cultivated carrot, yet little is known concerning the extent of their diversity in nature. Of special interest is an SNP in the putative stop codon of the mitochondrial gene atp9 that has been associated previously with male-sterile and male-fertile phenotypic variants. In this study, either the sequence or PCR/RFLP genotypes were obtained from the mitochondrial genes atp1, atp9, and cox1 found in D. carota individuals collected from 24 populations in the eastern United States. More than half of the 128 individuals surveyed had a CAA or AAA, rather than TAA, genotype at the position usually thought to function as an atp9 stop codon in this species. We also found no evidence for mitochondrial RNA editing (Cytosine to Uridine) of the CAA stop codon in either floral or leaf tissue. Evidence for intragenic recombination, as opposed to the more common intergenic recombination in plant mitochondrial genomes, in our data set is presented. Indel and SNP variants elsewhere in atp9, and in the other 2 genes surveyed, were nonrandomly associated with the 3 atp9 stop codon variants, though further analysis suggested that multilocus genotypic diversity had been enhanced by recombination. Overall the mitochondrial genetic diversity was only modestly structured among populations with an F(ST) of 0.34.     

Mutation of two intramembrane polar residues conserved within the hyaluronan synthase family alters hyaluronan product size

We identified two conserved polar amino acids within different membrane domains (MD) of Streptococcus equisimilis hyaluronan synthase (seHAS), Lys48 in MD2 and Glu327 in MD4. In eukaryotic HASs, the position of the Glu is very similar and the Lys is replaced by a conserved polar Gln. To assess whether Lys48 and Glu327 interact or influence seHAS activity, we investigated the effects of changing Lys48 to Arg or Glu and Glu327 to Lys, Asp, or Gln. Mutants, including a double switch variant with Lys48 and Glu327 exchanged, were expressed and assayed in Escherichia coli membranes. SeHASE327Q and seHASE327K were expressed at low levels, whereas seHASE327D and the Lys48 mutants were expressed well. The specific enzyme activities (relative to wild type) were 17 and 7% for the K48R and K48E mutants and 26 and 38% for the E327Q and E327D mutants, respectively. In contrast, seHAS(E327K) showed only 0.16% of wild-type activity but was rescued over 46-fold by changing Lys48 to Glu. Expression of the seHASE327K,K48E protein was also rescued to near wild-type levels. Based on size exclusion chromatography coupled to multiangle laser light scattering analysis, all the variants synthesized hyaluronan (HA) of smaller weight-average molar mass than wild-type enzyme (3.6 MDa); the smallest HA (approximately 0.6 MDa) was made by seHASE327K,K48E and seHASK48E. The results indicate that Glu327 within MD4 is a critical residue for the stability of seHAS, that it may interact with Lys48 within MD2, and that these residues are involved in the ability of HAS to synthesize very large HA.     

P53 codon 11, 72, and 248 gene polymorphisms in endometriosis

OBJECTIVE: Mutated p53 gene is related to the instability of cell growth and cell cycle progression. We aimed to evaluate the association between endometriosis and p53 codon 11, 72 and 248 gene polymorphisms.PATIENTS AND METHODS: Women were divided into two groups: (1) moderate/severe endometriosis (n=148), and (2) non-endometriosis groups (n=150). P53 gene polymorphisms include codon11 Glu/Gln or Lys (GAG->CAG or AAG), codon 72 Arg/Pro (CGC->CCC), and codon 248 Arg/Thr (CGG->TCG). These gene polymorphisms were amplified by polymerase chain reaction and detected by electrophoresis after restriction enzyme (Taq I, BstU I, Hap II) digestions. Associations between the endometriosis and p53 polymorphisms were evaluated.RESULTS: The distributions of p53 codon 72 polymorphisms in both groups were significantly different. The proportions of Arg homozygotes/heterozygotes/Pro homozygotes in both groups were 9.5/66.2/24.3% and 30.7/50/19.3%. The proportions of Arg/Pro alleles were 42.6/57.4% and 56/44%. The distributions of p53 codon 11 and 248 polymorphisms in both groups were non-significantly different. All individuals appeared the wild genotypes (Glu11 and Arg248 homozygotes).CONCLUSION: Association between endometriosis and p53 codon 72 polymorphism exists. P53 codon 72*Pro-related genotype and allele are related with higher susceptibility of endometriosis. P53 codon 11 and 248 polymorphisms are not related with endometriosis susceptibility.     

Nonsense and missense translational suppression in plant cells mediated by tRNALys

A nuclear tRNA^Lys gene from Arabidopsis thaliana was cloned and mutated so as to express tRNAs with altered anticodons which bind to a UAG nonsense (amber) codon and to the Arg (AGG), Asn (AAC,AAT), Gln (CAG) or Glu (GAG) codons. Concomitantly, a codon in the firefly luciferase gene for a functionally important Lys was altered to an amber codon, or to Arg, Asn, Gln, Glu, Thr and Trp codons, so as to construct reporter genes reliant upon incorporation of Lys. The altered tRNA^Lys and luciferase genes were introduced into Nicotiana benthamiana protoplasts and expression of the mutated tRNAs was verified by translational suppression of the mutant firefly luciferase genes. Expression of the amber suppressor tRNA _CUA ^Lys from non-replicative vectors promoted 10–40% suppression of the luciferase nonsense reporters while expression of the amber and missense tRNA^Lys suppressor genes from a geminivirus vector capable of replication promoted 30–80% suppression of the luciferase nonsense reporter and up to 10% suppression of the luciferase missense reporters with Arg, Asn, Gln and Glu codons.     

Unusual anticodon loop structure found in E.coli lysine tRNA.

Although both tRNA(Lys) and tRNA(Glu) of E. coli possess similar anticodon loop sequences, with the same hypermodified nucleoside 5-methylaminomethyl-2-thiouridine (mnm5s2U) at the first position of their anticodons, the anticodon loop structures of these two tRNAs containing the modified nucleoside appear to be quite different as judged from the following observations. (1) The CD band derived from the mnm5s2U residue is negative for tRNA(Glu), but positive for tRNA(Lys). (2) The mnm5s2U monomer itself and the mnm5s2U-containing anticodon loop fragment of tRNA(Lys) show the same negative CD bands as that of tRNA(Glu). (3) The positive CD band of tRNA(Lys) changes to negative when the temperature is raised. (4) The reactivity of the mnm5s2U residue toward H2O2 is much lower for tRNA(Lys) than for tRNA(Glu). These features suggest that tRNA(Lys) has an unusual anticodon loop structure, in which the mnm5s2U residue takes a different conformation from that of tRNA(Glu); whereas the mnm5s2U base of tRNA(Glu) has no direct bonding with other bases and is accessible to a solvent, that of tRNA(Lys) exists as if in some way buried in its anticodon loop. The limited hydrolysis of both tRNAs by various RNases suggests that some differences exist in the higher order structures of tRNA(Lys) and tRNA(Glu). The influence of the unusual anticodon loop structure observed for tRNA(Lys) on its function in the translational process is also discussed.