Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Protein S5 and S12 were isolated from 30S ribosomal subunits of two E. coli mutants highly resistant to the antibiotic neamine, and of the parental strain. Proteinchemical analyses on these proteins led to the following results: a) In protein S5 the arginine residue in peptide T2 of the parental strain is replaced by glycine in one (nea 314) or serine in the other (nea 319) of the two mutants. b) In protein S12 The proline residue in peptide T15 of the parental strain is replaced by leucine in mutant nea 314 and by glutamine in mutant nea 319. Comparison of these results with those obtained in earlier studies on other mutants with altered ribosomal proteins revealed that the amino acid replacements in neamine resistant mutants and in "revertants" from streptomycin dependence occur at the same amino acid positions of proteins S5 and S12. Therefore it is likely that both types of mutants belong to the same class.
Mol Gen Genet 1975 Dec 23
PMID:Cooperative control of translational fidelity by ribosomal proteins in Escherichia coli. II. Localization of amino acid replacements in proteins S5 and S12 altered in double mutants resistant to neamine. 76 36

1. The characteristics of absorption of individual amino acids from amino acid mixtures simulating casein and from enzymic hydrolysates of casein containing oligopeptides as well as free amino acids are known to be different. The differences, which are attributable to mucosal uptake of small peptides, involve more rapid absorption from the enzymic hydrolysates of certain amino acids which are relatively slowly absorbed from the amino acid mixtures. This could lead to more effective utilization of amino acids from the enzymic hydrolysates than from the amino acid mixtures. 2. To obtain further information bearing on this hypothesis, we have used a recently developed technique for portal cannulation in the guinea pig to make a preliminary investigation of amino acid concentrations in the portal venous plasma at intervals after the infusion into the duodenum of equivalent amounts of (a) an amino acid mixture simulating casein and (b) a partial enzymic (papain followed by kidney peptidases) hydrolysate of casein, the two preparations being infused in separate experiments. 3. For some amino acids, such as leucine, isoleucine, valine, phenylalanine and lysine, the curves after the enzymic hydrolysate were fairly similar to the corresponding curves after the amino acid mixture, though usually slightly lower. With other amino acids, the curves after the enzymic hydrolysate were very much lower than the corresponding curves after the amino acid mixture. With serine, glutamine, proline and glycine this discrepancy was particularly great. 4. The results cannot yet be fully explained, but their main features are explicable by the hypothesis that the lower amino acid concentrations in portal plasma after the enzymic hydrolysate are the result of entry of amino acids into the portal blood in peptide form, in which they would not be detectable by the analytical technique employed, and possibly also of more rapid clearance of amino acids from the blood during absorption of this preparation.
Clin Sci Mol Med 1977 Mar
PMID:Amino acid concentrations in portal venous plasma during absorption from the small intestine of the guinea pig of an amino acid mixture simulating casein and a partial enzymic hydrolysate of casein. 84 57

1. A jejunal perfusion technique has been used in normal volunteer subjects to study jejunal absorption of amino acid residues from a partial enzymic hydrolysate of casein in which about 50% of the amino acids existed as small peptides, and also from an equivalent mixture of free amino acids. 2. The effect of a high concentration of the dipeptide glycylglycine on the absorption of amino acid residues from these preparations was studied to quantify the importance of mucosal uptake of intact peptides during absorption of the partial hydrolysate of casein. 3. The results were unexpected. Glycylglycine significantly inhibited absorption of several amino acid residues (aspartic acid + asparagine, serine, glutamic acid + glutamine, proline, alanine, phenylalanine, threonine and isoleucine) from the free amino acid mixture, whereas it significantly inhibited the absorption of only two (serine, glutamin acid + glutamine) from the peptide-containing partial casein hydrolysate. 4. The effect of glycylglycine on absorption of amino acids from the mixture of free amino acids was apparently due to inhibition of amino acid uptake by free glycine liberated from the dipeptide during perfusion. The reason for the failure of glycylglycine to cause extensive inhibition of absorption from the partial hydrolysate is not clear. It may be due to glycylglycine being only a weak inhibitor of peptide uptake, but the possibility that some peptides are taken up by a system unavailable to glycylglycine has to be considered.
Clin Sci Mol Med 1977 Jul
PMID:Effect of glycylglycine on absorption from human jejunum of an amino acid mixture simulating casein and a partial enzymic hydrolysate of casein containing small peptides. 87 18

1. Administration of dexamethasone, 8 mg/day (0-02 mmol/day), for 5 days to normal subjects produced negative nitrogen balance, due to early and sustained increases in urinary urea nitrogen excretion 2. In eight subjects ingesting 0-9--1-6 g of protein day-1 kg-1 body weight the cumulative increment in urea nitrogen excretion averaged + 12-5 g (SEM 2-8, P less than 0-01) over the 5 days of glucocorticoid administration. 3. Increases in urinary urea nitrogen excretion could be related to both plasma alanine and blood glutamine changes by using a multiple regression equation. 4. These results suggest that corticosteroids induce increased release of alanine and glutamine by peripheral tissues, which may augment urea formation and negative nitrogen balance. 5. The correlation between increments in urea nitrogen excretion and increases in plasma arginine remains unexplained.
Clin Sci Mol Med 1977 Sep
PMID:The role of alanine and glutamine in steroid-induced nitrogen wasting in man. 91 44

1. Two women with severe hypokalaemic alkalosis were investigated by means of muscle biopsy before and at the end of 2 and 3 weeks respectively of intense therapy with potassium chloride. 2. The muscle biopsy material was analysed for water, electrolytes, adenine nucleotides, phosphocreatine, free creatine, pyruvate, lactate, glycogen and free amino acids. The extra- and intra-cellular distribution of water, electrolytes and amino acids was calculated by the chloride method. 3. Both patients showed a marked loss of intracellular potassium and an increase in intracellular sodium concentration. The muscle magnesium content was also slightly decreased. After repletion with potassium chloride, muscle sodium and potassium became normal. 4. The contents of creatine phosphate, ATP, ADP, AMP, lactate and pyruvate were within normal limits, but the phosphocreatine/total creatine ratio was reduced. After repletion, a small change in the apparent creatine-phosphokinase equilibrium had occurred, suggesting a minor increase in intracellular pH. 5. The concentrations of the basic amino acids, lysine, arginine and ornithine were increased far above normal. The intracellular accumulation of arginine was much higher than the increase in lysine concentration and histidine concentration was normal. This differs from findings in potassium-depleted rats, where the intracellular lysine concentration is much higher than arginine concentration and histidine is high as well. After potassium repletion the intracellular concentration of ornithine, lysine and arginine became normal in one case and decreased considerable in the other. An increased intracellular concentration of glutamate and glutamine was also observed after potassium repletion.
Clin Sci Mol Med 1976 Dec
PMID:Influence of severe potassium depletion and subsequent repletion with potassium on muscle electrolytes, metabolites and amino acids in man. 107 Apr 23

Two classes of Salmonella typhimurium mutants resistant to inhibitory methionine analogues and defective in methionine transport have been examined. A mutant of the first class, resistant to alpha-methylmethionine, was shown by conjugation analysis to possess a single mutation in the metP gene which specifies a methionine transport system. Mutants of the second class, resistant to alpha-methylmethionine and methionine sulphoximine, possess two mutations. One is in the metP gene, which accounts for resistance to alpha-methylmethionine, and the other is in a gene designated glnP which results in reduced L-glutamine transport. Both of these mutations are required for resistance to methionine sulphoximine. A transduction analysis of three metP mutations was performed, based on the fact that they prevent growth of methionine-requiring strains on D-methionine. Two of the mutants are closely linked and therefore probably in the same gene, whereas the third mutant might be in a different gene.
Mol Gen Genet 1975
PMID:The role of methionine transport-defective mutations in resistance to methionine sulphoximine in Salmonella typhimurium. 110 23

Proteins S4 and S12 were isolated from ribosomes of three mutants of Escherichia coli in which dependence on streptomycin caused by alteration in protein S12 is suppressed by an altered protein S4. Proteinchemical studies on the mutant proteins gave the following results: Proteins S12 from all three mutants differ from S12 of the wild type by the replacement of proline to leucine in peptide T15. In all mutant S4 proteins a replacement og glutamine to leucine at amino acid position 53 was found. In addition to this replacement at position 53 a glutamic acid residue at position 199 near the C-terminus was deleted in one of the three mutants. However, this deletion is not necessary for the ability of the mutant S4 protein to suppress dependence on streptomycin. The results support the hypothesis that ram mutants and "revertants" from streptomycin dependence to independence belong to the same class although they were isolated by different selection procedures.
Mol Gen Genet 1975 Sep 15
PMID:Proteinchemical studies on ribosomal proteins S4 and S12 from ram (ribosomal ambiguity) mutants of Escherichia coli. 110 52

A model is proposed for the structure of stereospecific sites in regulatory proteins. On its basis a possible code is suggested that governs the binding of regulatory proteins at specific control sites on DNA. Stereospecific sites of regulatory proteins are assumed to contain pairs of antiparallel polypeptide chain segments which form a right-hand twisted antiparallel beta-sheet, with single-stranded regions at the ends of the beta-structure. The model predicts that binding reaction between a regulatory protein and double-helical DNA is a cooperative phenomenon and is accompanied by significant structural alteration at the stereospecific site of the protein. Half of hydrogen bonds normally existing in beta-structure are broken upon complex formation with DNA and a new set of hydrogen bonds is formed between polypeptide amide groups and DNA base pairs. In a stereospecific site, one chain (t-chain) is attached through hydrogen bonds to the carbonyl oxygens of pyramides and N3 adenines lying in one DNA strand, while the second polypeptide chain (g chain) is hydrogen bonded to the 2-amino groups of guanine residues lying in the opposite DNA strand. The amide groups serve as specific reaction sites being hydrogen bond acceptors in g-chain and hydrogen bond donors in t-chain. The single-stranded portions of t- and g-chains lying in neighbouring subunits of regulatory protein interact with each other forming deformed beta-sheets. The recognition of regulatory sequences by proteins is based on the structural complementarity between stereospecific sites of regulatory proteins and base pairs sequences at the control sites. An essential feature of these sequences is the asymmetrical distribution of guanine residues between the two DNA strands. The code predicts that there are six fundamental amino acid residues (serine, threonine, asparagine, histidine, glutamine and cysteine) whose sequence in stereospecific site determines the base pair sequence to which a given regulatory protein would bind preferentially. The code states a correspondence between four amino acid residues at the stereospecific site of regulatory protein with the two residues being in t- and g-segments, respectively, and AT(GC) base pair at the control site. It is thus possible to determine which amino acid residues in the repressor and which base pairs in the operator DNA are involved in specific interactions with each other, as exemplified by lac repressor binding to lac operator.
Mol Biol (Mosk)
PMID:[A code governing specific binding of regulatory proteins to DNA and structure of stereospecific sites of regulatory proteins]. 121 4

A possible code is suggested that describes a correspondence between amino acid sequences in stereospecific sites of regulatory proteins and nucleotide sequences at the control sites on DNA. Stereospecific sites of regulatory proteins are assumed to contain pairs of antiparallel polypeptide chain segments which form a right-hand twisted antiparallel beta-sheet with single-stranded regions at the ends of the beta-structure. The binding reaction between regulatory protein and double-helical DNA is accompanied by significant structural alterations at stereospecific sites of the protein and DNA. Half of the hydrogen bonds normally existing in beta-structure are broken upon complex formation with DNA and a new set of hydrogen bonds is formed between polypeptide amide groups and DNA base pairs. The code states a correspondence between four amino acid residues at a stereospecific site of the regulatory protein and an AT (GC) base pair at the control site. It predicts that there are six fundamental amino acid residues (serine, threonine, histidine, asparagine, glutamine and cysteine) whose arrangement in the stereospecific site determines the base pair sequence to which a given regulatory protein would bind preferentially.
Mol Biol Rep 1976 Apr
PMID:A code controlling specific binding of regulatory proteins to DNA. 127 65

1. Gluconeogenesis from lactate or from glutamine is inhibited by 90-100% by sodium quinolinate (1 mmol/l) or 3-mercaptopicolinate (150 nmol/l) in the perfused rat kidney. L-Tryptophan is not metabolized and is without effect. 2. Lactate uptake and glucose production are inhibited to the same degree by 3-mercaptopicolinate in the kidneys of well-fed or starved rats. 3. Inhibition of gluconeogenesis from glutamine (1 mmol/l) by 3-mercaptopicolinate is accompanied by 50% inhibition of ammonia production, and 34% inhibition of glutamine uptake, in the kidneys of acidotic rats. Ammonia production from glutamine was not inhibited in kidneys from non-acidotic rats. 4. It is concluded that the increased rate of gluconeogenesis from glutamine which occurs in acidotic rats is an essential and primary event regulating all of the increase in ammonia formation.
Clin Sci Mol Med 1976 Jun
PMID:Effect of inhibition of gluconeogenesis on ammonia production in the perfused rat kidney. 127 56


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