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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A kinetic study of the influence of thyreotrope-releasing hormone (TRH) on prolactin turnover and synthesis by a new rat pituitary prolactin cell line (SD1) has been performed by means of pulse-chase experiments. After a 10-min [3H]leucine pulse, the chase was carried out in the presence or absence of TRH (54 nM), cycloheximide (3.6 X 10(-5)M) and/or [14C]-proline. The prolactin content of the cells in the medium was estimated using a radioimmunoassay technique. The specific radioactivity of prolactin in the medium was estimated after its isolation by disc gel electrophoresis. This kinetic study demonstrated, firstly, a rapid intracellular transit of newly synthesized prolactin (15 + 10 min or less); secondly, the existence of at least two intracellular prolactin pools; thirdly, a rapid effect of TRH on release of stored prolactin, which is independent of de novo protein synthesis, and fourthly, a delayed stimulating effect of TRH on prolactin synthesis.
Mol Cell Endocrinol 1975 Nov
PMID:Effect of thyreotrope-releasing hormone (TRH) on prolactin turnover in culture. 81 96

The incorporation of 3H from [3H]leucine into protein in various regions of the brain and in the anterior pituitary was measured at 6-h intervals throughout a 24-h period in groups of male and female rats. No rhythm was observed in the male, while there were significant circadian rhythms in certain areas of the female brain, with peaks at 15.00 h. Statistically significant rhythms of the acid-soluble tritium and of the protein concentrations in the individual tissues were also observed, but were unrelated to the rhythms of incorporation of the label into protein.
Mol Cell Endocrinol 1977 Feb
PMID:Circadian [3H] leucine incorporation into protein of the rat brain: sex differences. 83 19

1. Sham-operated and bilaterally nephrectomized rats were injected intravenously with glycyl-L-leucine, glycylglycine and glycylsarcosine, and the concentrations of these dipeptides in plasma and muscle, liver, renal cortex (in the sham-operated rats) and intestinal mucosa at various intervals were determined. 2. Initially the plasma concentrations of glycyl-leucine and glycylglycine were higher in nephrectomized than in control rats but later the concentrations were similar in both groups of rats. The disappearance of these two dipeptides from plasma was almost complete within 20 min, and their plasma half-lives were not changed remarkably by nephrectomy. In contrast, nephrectomy markedly impaired disappearance of glycylsarcosine from plasma and prolonged its half-life from 7-6 min to 52-0 min. 3. Glycyl-leucine and glycylglycine were not detected in tissues of control rats injected with these dipeptides, but glycylsarcosine was recovered from all four tissues examined. Nephrectomy resulted in greater accumulations of glycylsarcosine in tissues and the appearance of glycylglycine in the remaining three tissues and glycyl-leucine in muscle. 4. Enterectomy did not have a remarkable effect on plasma half-life of glycylglycine but it allowed recovery of this dipeptide from renal cortex, liver and muscle. 5. It is concluded that kidneys amd small intestine are involved in the disposition of circulating dipeptides, but in their absence other tissues may assume a greater role in this regard. However, renal clearance appears to be an important route for the disposition of dipeptides which are poorly hydrolysed by body tissues.
Clin Sci Mol Med 1977 Feb
PMID:Effect of nephrectomy and enterectomy on plasma clearance of intravenously administered dipeptides in rats. 84 52

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

In MCF-7 human breast cancer cells, insulin stimulated the rate of [3H]uridine incorporation into RNA, [3H]thymidine incorporation into DNA, and [3H]leucine incorporation into protein. In addition, hydrocortisone appeared to augment the effect of insulin, by further increasing the rate of [3H]uridine incorporation into RNA and [3H]thymidine incorporation into DNA. A significant increase in the total amount of DNA and protein was present in cultures treated with insulin compared to untreated controls. Hydrocortisone was shown to augment the insulin effect on total protein accumulation and total RNA accumulation in MCF-7 cells.
Mol Cell Endocrinol 1977 Jun
PMID:Hydrocortisone enhancement of insulin's action on macromolecular synthesis in MCF-7 cells. 88 87

The A-protein of coliphage MS2 was purified to a state of sufficient homogeneity to study its primary structure. The NH2-terminal sequence was determined for the first 8 residues. Comparison with the reported sequence of R17 protein (Weiner, A. M., Platt, T., and Weber, K. (1972) J. Biol. Chem. 247, 3242-3251) shows a difference at position 6 where alanine in R17 is replaced by threonine in MS2. The COOH-terminal sequence was shown to be -Arg-Leu-Ser-Arg, confirming the existence of UAG as the termination codon of the maturation protein (Comtreras, R., Ysebaert, M., Min Jou, W., and Fiers, W. (19731 Nature New Biol. 241, 99-101; Vandekerckhove, J., Nolf, F., and Van Montagu, M. C. (1973) Nature New Biol. 241, 102; Remaut E., and Fiers, W. (1972) J. Mol. Biol. 71, 243-261). Peptides obtained by enzymatic hydrolysis with trypsin were fractionated by a combination of gel filtration and paper electrophoresis and chromatography. Thirty-eight peptides were analyzed for amino acid composition and sequence. They provide information for 312 of the 393 residues of the A-protein polypeptide chain.
 ...
PMID:Sequence of the A-protein of coliphage MS2. I. Isolation of A-protein, determination of the NH2- and COOH-terminal sequences, isolation and amino acid sequence of the tryptic peptides. 91 36

Cycloheximide (5.0 mug/ml) had no significant effect on respiration of liver slices prepared from euthyroid rats (i.e., QO2 of 15.5 +/- 0.8 vs. 14.9 +/- 0.8 mul/mg protein) despite an 83.8 +/- 2.1% inhibition of protein synthesis as judged by [3H]leucine incorporation into the trichloroacetic acid precipitable fraction. Injection of triiodothyronine increased the QO2 of rat liver slices to 22.6 +/- 1.1 mul/h/mg protein. The QO2 of hyperthyroid slices remained high in the presence of cycloheximide although protein synthesis was inhibited by 84.4 +/- 2.0%. These results imply that the energy requirement for protein synthesis contributes little to QO2 of euthyroid liver and does not account for a significant fraction of the increase in hepatic QO2 obtained in the transition from the euthyroid to the hyperthyroid state.
Mol Cell Endocrinol
PMID:Thyroid thermogenesis: minimal contribution of energy requirement for protein synthesis. 95 45

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

The contacts between bulky hydrophobic side chains (Val, Leu, Ile, Met, Phe, Tyr, and Trp) were studied in five globins with known three-dimensional structures. It is shown that a large majority of these side chains participate in such contacts, where most often one side chain makes contact with two to four nearby side chains. The "recognition element" of a helical region is most often a pair of bulky hydrophobic side chains belinging to neighboring turns of an alpha-helix. Such pairs most often make contact with bulky hydrophobic side chains brought in from the outside. An analysis is made of contacts between the hydrophobic side chains common to all five globins. It is shown that as a rule the most intense contacts in each globin are also common to the five globins. The role of these invariant contacts in the formation of the tertiary structure of globin molecules is considered. A suggestion is made that the apoglobin molecule consists of independently self-organizing halves, the internal structure of which is less subject to fluctuation than their mutual arrangement.
Mol Biol 1975 Jan
PMID:The structure of hydrophobic cores of globins. 112 3

Rough endoplasmic reticulum was reconstituted from free polyribosomes and rough membrane stripped from its ribosomes by KCl and puromycin. The reconstituted rough membrane resembled the native rough membrane in the following aspects: RNA/protein ratio, buoyant density in a continuous sucrose gradient, amino acid incorporation capacity and sensitivity towards protein synthesis inhibitors. When the reconstitution was done with double labelled polyribosomes ([32-P] polyribosomes, [3-H] leucine labelling of nascent peptide chain before or after the attachment of the polyribosomes to the membrane) both labels banded together with the reconstituted rough membrane band. Hybrid rough membrane could be formed from rat liver stripped rough membrane and wheat germ ribosomes. This hybrid membrane could translate globin mRNA.
Mol Biol Rep 1975 Mar
PMID:The in vitro reconstitution of a functional rough membrane active in protein synthesis. 112 17


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