Sulfur amino acid metabolism in the whole body and mammary gland of the lactating Saanen goat

1999 ◽  
Vol 50 (3) ◽  
pp. 413 ◽  
Author(s):  
J. Lee ◽  
R. J. Knutson ◽  
S. R. Davis ◽  
K. Louie ◽  
D. D. S. Mackenzie ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Significant Proportion ◽  
Oxidation Products ◽  
Whole Body ◽  
Acid Uptake ◽  
Saanen Goat ◽  
Arterial Blood

Five multiparous Saanen goats in late lactation were infused with 35S-cysteine into the mammary gland via the external pudic artery. A further 2 goats were infused with 35S-methionine via the same artery and later with 35S-methionine into the jugular vein. Total uptake of cysteine from the arterial blood supply by the mammary gland was approximately 6% of the 35S-cysteine flux past the gland, whereas uptake of methionine was 30–40%. Total mammary uptake of cysteine was also lower than that of methionine when expressed as a percentage of whole body utilisation (6.5 and 14%, respectively). The uptake from the blood did not account for output in the milk for either cysteine or methionine. Both amino acids were highly conserved by the gland as shown by little release of any degraded constitutive protein amino acids and no evidence of oxidation products of either cysteine or methionine being released into the blood. Comparison of 35S activity in the milk from the infused and non-infused sides of the gland showed up to 10% trans-sulfuration of methionine to cysteine within the gland, none of which was exported in the venous drainage. Total ATP production by one side of the gland was 12.1 mol/day or 13 mmol/min.kg mammary tissue, of which 15% was required for gland protein synthesis. The experimental measurements from both the cysteine and methionine infusions were used to solve a model of gland amino acid uptake and partitioning. Modelling radioactivity of both amino acids in the blood, intracellular free pool, and milk protein suggested that a single intracellular pool cannot be the only source of amino acid for protein synthesis. The model also provides support for the hypothesis that a significant proportion of the uptake of at least some amino acids by the mammary gland is from intracellular hydrolysis of extracellularly derived peptides.

Effects of increased supply of essential amino acids on the metabolism of the isolated perfused guinea-pig mammary gland

1979 ◽  
Vol 46 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Andrew R. Peters ◽  
Stephen Alexandrov ◽  
T. Ben Mepham
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Guinea Pig ◽  
Amino Acid Uptake ◽  
Essential Amino Acids ◽  
Acid Uptake ◽  
Isoleucine Leucine ◽  
Group 1

SUMMARYThe effects of high rates of infusion of essential amino acids on amino acid uptake by the isolated perfused guinea-pig mammary gland were studied. Infusion of methionine, tyrosine, phenylalanine, histidine and tryptophan (designated group 1) resulted in significant increases in the uptakes of tyrosine, phenylalanine and histidine. Methionine, tryptophan and other essential amino acids were not significantly affected. Infusion of threonine, valine, isoleucine, leucine, lysine and arginine (designated group 2) resulted in significant increases in uptake of all these amino acids. Group 1 amino acid uptake was not significantly affected. Infusion of all the essential amino acids (i.e. groups 1 and 2 together) resulted in significant increases in all their uptakes. Using as index ‘the predicted rate of protein synthesis’, infusion of group 1 and 2 together led to an apparent 27% increase in protein synthesis. The above results are discussed in relation to the control of milk protein synthesis by limiting essential amino acids.

Gamma-Glutamyl-Amino Acids as Signals for the Hormonal Regulation of Amino Acid Uptake by the Mammary Gland of the Lactating Rat

Neonatology ◽  
1985 ◽  
Vol 48 (4) ◽  
pp. 250-256 ◽  
Author(s):  
Juan R. Viña ◽  
Inmaculada R. Puertes ◽  
Juan B. Montoro ◽  
Guillermo T. Saez ◽  
José Viña
Keyword(s):  
Amino Acids ◽  
Mammary Gland ◽  
Amino Acid ◽  
Hormonal Regulation ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Gamma Glutamyl

scholarly journals Action of growth hormone in vitro on the net uptake and incorporation into protein of amino acids in muscle from intact rabbits given protein-deficient diets

1976 ◽  
Vol 35 (1) ◽  
pp. 1-10 ◽  
Author(s):  
M. R. Turner ◽  
P. J. Reeds ◽  
K. A. Munday
Keyword(s):  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Amino Acid ◽  
De Novo ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Amino Acid Incorporation ◽  
Acid Incorporation

1. Net amino acid uptake, and incorporation into protein have been measured in vitro in the presence and absence of porcine growth hormone (GH) in muscle from intact rabbits fed for 5 d on low-protein (LP), protein-free (PF) or control diets.2. In muscle from control and LP animals GH had no effect on the net amino acid uptake but stimulated amino acid incorporation into protein, although this response was less in LP animals than in control animals.3. In muscle from PF animals, GH stimulated both amino acid incorporation into protein and the net amino acid uptake, a type of response which also occurs in hypophysectomized animals. The magnitude of the effect of GH on the incorporation of amino acids into protein was reduced in muscle from PF animals.4. The effect of GH on the net amino acid uptake in PF animals was completely blocked by cycloheximide; the uptake effect of GH in these animals was dependent therefore on de novo protein synthesis.5. It is proposed that in the adult the role of growth hormone in protein metabolism is to sustain cellular protein synthesis when there is a decrease in the level of substrate amino acids, similar to that which occurs during a short-term fast or when the dietary protein intake is inadequate.

scholarly journals Action of insulin and growth hormone on protein synthesis in muscle from non-hypophysectomized rabbits

1971 ◽  
Vol 125 (2) ◽  
pp. 515-520 ◽  
Author(s):  
P. J. Reeds ◽  
K. A. Munday ◽  
M. R. Turner
Keyword(s):  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Incubation Medium ◽  
Amino Acid Uptake ◽  
Diaphragm Muscle ◽  
Acid Uptake

The separate effects of insulin and growth hormone on the uptake and incorporation of five amino acids into diaphragm muscle from non-hypophysectomized rabbits has been examined. Both growth hormone and insulin, when present in the medium separately, stimulated the incorporation into protein of the amino acids, leucine, arginine, valine, lysine and histidine. Insulin also stimulated amino acid uptake, but growth hormone did not. When insulin and growth hormone were present in the incubation medium together, the uptake and incorporation of valine, the only amino acid studied under these conditions, tended to be greater than the sum of the separate effects of the two hormones.

Protein and energy metabolism in the pre-implantation cattle embryo

2001 ◽  
Vol 26 (2) ◽  
pp. 443-446 ◽  
Author(s):  
D.G. Morris ◽  
P. Humpherson ◽  
H.J. Leese ◽  
J.M. Sreenan
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Energy Metabolism ◽  
Metabolic Rate ◽  
Protein Content ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Glucose Utilisation ◽  
Embryonic Loss

AbstractThere is no information on the metabolism of the cattle embryo during the period from day 8 to 16 a period of greatest embryonic loss. In this study the rate of protein synthesis and phosphorylation was measured in 13 to 15 day old cattle embryos. The rate of glucose utilisation and amino acid uptake/efflux by day 14 to 16 embryos was also measured. Protein synthesis and phosphorylation activity when expressed per unit of protein decreased with increasing embryo size and age. Similarly the rate of glucose utilisation was greatest for the earlier day 14 embryos. Embryos differed in their requirement for different amino acids. The pattern of uptake/efflux was similar to that of the earlier day 7 embryo. This study suggests that the metabolic rate of cattle embryos expressed per unit of protein content tends to decrease with increasing age and size from the initial burst of activity at day 13 around the time that expansion of the embryo begins.

Suppression of muscle protein turnover and amino acid degradation by dietary protein deficiency

1992 ◽  
Vol 263 (2) ◽  
pp. E317-E325 ◽  
Author(s):  
N. E. Tawa ◽  
A. L. Goldberg
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Dietary Protein ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Normal Diet ◽  
High Rate ◽  
Acid Uptake ◽  
Rapid Weight Gain

To define the adaptations that conserve amino acids and muscle protein when dietary protein intake is inadequate, rats (60-70 g final wt) were fed a normal or protein-deficient (PD) diet (18 or 1% lactalbumin), and their muscles were studied in vitro. After 7 days on the PD diet, both protein degradation and synthesis fell 30-40% in skeletal muscles and atria. This fall in proteolysis did not result from reduced amino acid supply to the muscle and preceded any clear decrease in plasma amino acids. Oxidation of branched-chain amino acids, glutamine and alanine synthesis, and uptake of alpha-aminoisobutyrate also fell by 30-50% in muscles and adipose tissue of PD rats. After 1 day on the PD diet, muscle protein synthesis and amino acid uptake decreased by 25-40%, and after 3 days proteolysis and leucine oxidation fell 30-45%. Upon refeeding with the normal diet, protein synthesis also rose more rapidly (+30% by 1 day) than proteolysis, which increased significantly after 3 days (+60%). These different time courses suggest distinct endocrine signals for these responses. The high rate of protein synthesis and low rate of proteolysis during the first 3 days of refeeding a normal diet to PD rats contributes to the rapid weight gain ("catch-up growth") of such animals.

scholarly journals PROTEIN SYNTHESIS IN ISOLATED CELL NUCLEI

1957 ◽  
Vol 40 (3) ◽  
pp. 451-490 ◽  
Author(s):  
V. G. Allfrey ◽  
A. E. Mirsky ◽  
Syozo Osawa
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Ribonucleic Acid ◽  
Orotic Acid ◽  
Nuclear Protein ◽  
Acid Uptake ◽  
Amino Acid Incorporation ◽  
Acid Incorporation ◽  
Thymus Tissue

1. Nuclei prepared from calf thymus tissue in a sucrose medium actively incorporate labelled amino acids into their proteins. This is an aerobic process which is dependent on nuclear oxidative phosphorylation. 2. Evidence is presented to show that the uptake of amino acids represents nuclear protein synthesis. 3. The deoxyribonucleic acid of the nucleus plays a role in amino acid incorporation. Protein synthesis virtually ceases when the DNA is removed from the nucleus, and uptake resumes when the DNA is restored. 4. In the essential mechanism of amino acid incorporation, the role of the DNA can be filled by denatured or partially degraded DNA, by DNAs from other tissues, and even by RNA. Purine and pyrimidine bases, monoribonucleotides, and certain dinucleotides are unable to substitute for DNA in this system. 5. When the proteins of the nucleus are fractionated and classified according to their specific activities, one finds the histones to be relatively inert. The protein fraction most closely associated with the DNA has a very high activity. A readily extractable ribonucleoprotein complex is also extremely active, and it is tempting to speculate that this may be an intermediary in nucleocytoplasmic interaction. 6. The isolated nucleus can incorporate glycine into nucleic acid purines, and orotic acid into the pyrimidines of its RNA. Orotic acid uptake into nuclear RNA requires the presence of the DNA. 7. The synthesis of ribonucleic acid can be inhibited at any time by a benzimidazole riboside (DRB) (which also retards influenza virus multiplication (11)). 8. The incorporation of amino acids into nuclear proteins seems to require a preliminary activation of the nucleus. This can be inhibited by the same benzimidazole derivative (DRB) which interferes with RNA synthesis, provided that the inhibitor is present at the outset of the incubation. DRB added 30 minutes later has no effect on nuclear protein synthesis. These results suggest that the activation of the nucleus so that it actively incorporates amino acids into its proteins requires a preliminary synthesis of ribonucleic acid. 9. Together with earlier observations (27, 28) on the incorporation of amino acids by cytoplasmic particulates, these results show that protein synthesis can occur in both nucleus and cytoplasm.

The role of amino acid transporters in inherited and acquired diseases

2011 ◽  
Vol 436 (2) ◽  
pp. 193-211 ◽  
Author(s):  
Stefan Bröer ◽  
Manuel Palacín
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Mammalian Cells ◽  
Neuronal Excitability ◽  
Tumour Progression ◽  
Building Blocks ◽  
Amino Acid Uptake ◽  
Whole Body ◽  
Amino Acid Transporters ◽  
Acid Uptake

Amino acids are essential building blocks of all mammalian cells. In addition to their role in protein synthesis, amino acids play an important role as energy fuels, precursors for a variety of metabolites and as signalling molecules. Disorders associated with the malfunction of amino acid transporters reflect the variety of roles that they fulfil in human physiology. Mutations of brain amino acid transporters affect neuronal excitability. Mutations of renal and intestinal amino acid transporters affect whole-body homoeostasis, resulting in malabsorption and renal problems. Amino acid transporters that are integral parts of metabolic pathways reduce the function of these pathways. Finally, amino acid uptake is essential for cell growth, thereby explaining their role in tumour progression. The present review summarizes the involvement of amino acid transporters in these roles as illustrated by diseases resulting from transporter malfunction.

scholarly journals Inhibitory effect of pH5 enzyme from non-lactating bovine mammary gland on various stages of protein synthesis in the rat liver amino acid-incorporating system

1969 ◽  
Vol 115 (4) ◽  
pp. 671-678 ◽  
Author(s):  
M. D. Herrington ◽  
A. O. Hawtrey
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Mammary Gland ◽  
Amino Acid ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Inhibitory Effect ◽  
Bovine Mammary Gland ◽  
Free System ◽  
Enzyme Fraction

1. pH5 enzyme from non-lactating bovine mammary gland was found to contain potent inhibitors of protein synthesis in the rat liver cell-free system. These inhibitors affect (a) formation of aminoacyl-tRNA where tRNA represents transfer RNA, (b) transfer of labelled amino acids from rat liver amino[14C]acyl-tRNA to protein in rat liver polyribosomes, and (c) incorporation of 14C-labelled amino acids into peptide by rat liver polyribosomes supplemented with rat liver pH5 enzyme. 2. Increasing amounts of pH5 enzyme from bovine mammary gland progressively inhibited the incorporation of labelled amino acids into protein by a complete incorporating system from rat liver. Approx. 80% inhibition was observed at a concentration of 2mg. of protein of pH5 enzyme from bovine mammary gland. The inhibitory effect of the bovine pH5 enzyme fraction could not be overcome by the addition of increasing amounts of rat liver pH5 enzyme. 3. Fractionation of bovine pH5 enzyme with ammonium sulphate into four fractions showed that all the fractions inhibited the incorporation of 14C-labelled amino acids in the rat liver system, but to varying extents. The highest inhibition observed (90%) was exhibited by the 60%-saturated-ammonium sulphate fraction. 4. Heat treatment of bovine pH5 enzyme at various temperatures caused only a partial loss of its inhibitory effect on labelled amino acid incorporation by the rat liver system. Treatment at 105° for 5min. resulted in the bovine pH5 enzyme fraction losing 30% of its inhibitory activity. 5. pH5 enzyme from bovine mammary gland strongly inhibited the charging of rat liver tRNA in the presence of its own pH5 enzymes. 6. The transfer of labelled amino acids from rat liver amino[14C]acyl-tRNA to protein in a system containing rat liver polyribosomes and pH5 enzyme was almost completely inhibited by bovine pH5 enzyme at a concentration of 2mg. of protein of the enzyme fraction. 7. One of the inhibitors of various stages of protein synthesis in rat liver present in bovine pH5 enzyme was identified as an active ribonuclease, and the second inhibitor present was shown to be tRNA.

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