Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00790 (PGA)
 2,475 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Incubation of rabbit choroid plexus, anterior uvea (iris-ciliary body complex) or slices of kidney cortex in a medium containing tritium-labelled prostaglandin F(2alpha) ([3H]PGF(2alpha) or E1 ([3H]PGE1) results in a four- to thirteenfold concentrative accumulation of 3H activity. 2. Addition of PGF(2alpha, PGF(1) or PGA(1), any one of five PG analogues or a PG precursor, arachidonic acid, at a concentration of 10(-4) M reduced the active accumulation of [3H]PGs by 47-97%. Octanoic acid, at the same concentration, had only a moderate effect on the choroid plexus and no significant inhibitory effect on [3H]PFG(2alpha) accumulation by anterior uvea or kidney cortex. 3. Inhibition was also obtained with 2 mM iodoacetate (under anaerobic conditions) and with 10(-4) M diploretin phosphate, probenecid, iodipamide, indomethacin or dinitrophenol. Perchlorate (10(-4) M) and iodide (10(-4) or 10(-3) M) had no inhibitory effect while 10(-4) M p-aminohippuric acid had a significant inhibitory effect on the kidney cortex at a concentration of 10(-4) M and on the anterior uvea at 10(-3) M. 4. It is concluded that the apparent carrier mediated PG transport systems of the choroid plexus, anterior uvea and kidney cortex are not related to the iodide transport system, but may represent a subcomponent of the iodipamide transport system of these tissues. 5. These results suggest that the systemic distribution and the rate of renal excretion of PGs could be altered by high concentrations of PGs, pharmacologically less active PG analogues, some inhibitors of organic acid transport, and by some inhibitors of PG synthesis and PG action.
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PMID:Inhibition of in vitro concentrative prostaglandin accumulation by prostaglandins, prostaglandin analogues and by some inhibitors of organic anion transport. 93 72

The flagellar complex of the unusual motile spermatozoon of the fungus gnat, Rhynchosciara sp, does not conform to the usual "9 + 2" filament pattern but rather consists of over 350 pairs of filaments (doublet microtubules) distributed in a spiral array. Experiments were designed to disrupt and extract flagellar microtubular components from spermatozoa of the fungus gnat. Pepsin, chymotrypsin, potassium iodide, urea, and heat were used to extract specific portions of microtubule walls Such experiments provide information on the composition of the wall and the existence of wall sites selectively sensitive to various treatments Results obtained include: (a) doublet microtubules are comprised at least in part of protein, and all subunits are probably not identical; (b) a portion of the B subfiber is apparently more sensitive to disruption than other portions of the doublet microtubule; and (c) the ac cessory singlet microtubules may be chemically different from the doublet microtubules
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PMID:Electron microscope studies of spermatozoa of Rhynchosciara Sp. I. Disruption of microtubules by various treatments. 504 61

Previously we described the simultaneous quantification of DNA and nuclear protein in unfixed tissue from solid tumors. The resultant 2 parameter flow cytometric analysis has several advantages over that of DNA alone. In this report, we describe a modification of the technique for the analysis of formalin-fixed paraffin-embedded tissue. Paraffin-embedded material was prepared by hydrating sections, incubating in 0.5% pepsin solution, washing, and resuspending in buffer containing nonionic detergent. The nuclei were then stained with fluorescein isothiocyanate and propidium iodide in the presence of ribonuclease. Several solid tumor tissue types have been analyzed, including breast, colon, kidney, and thymus. The best results were obtained when the initial pepsin treatment was for 1.5 h, instead of 0.5 h. Pepsin treatment for 1.5 h improved the CVs of both the DNA and nuclear protein parameters, and did not appear to reduce nuclear protein levels or to cause significant disintegration of nuclei. The DNA/nuclear protein histograms of unfixed and fixed, paraffin-embedded tissue were similar. Since tumor nuclei typically have higher protein levels than DNA-diploid nuclei, the technique reduces population overlapping and permits less subjective identification of DNA aneuploidy.
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PMID:Flow cytometric analysis of DNA and nuclear protein in paraffin-embedded tissue. 844 Jan 53

Mutagenesis of the large subunit (LS) of the potato ADP-glucose pyrophosphorylase generated an enzyme, P52L, that was insensitive to 3-phosphoglycerate (3-PGA). To identify additional residues involved in 3-PGA interaction, we subjected P52L LS DNA to a second round of mutagenesis and identified second-site revertants by their ability to restore glycogen accumulation as assessed by iodine (I2) staining. Enzymes from class I revertants with normal I2-staining had an 11- to 49-fold greater affinity for the activator 3-PGA compared with the P52L mutant and a decreased sensitivity to the inhibitor orthophosphate. Sequence analysis of these class I revertants identified a P66L mutation in R4, an E38K mutation in R20, and a G101N mutation in R10 and R32. These mutations appear to restore 3-PGA binding by counteracting the effect of the P52L mutation because introducing E38K or G101N into the wild-type LS led to enzyme variants with higher affinity for the activator 3-PGA and increased resistance to the inhibitor orthophosphate. The generation of these revertant enzymes provides additional structure-function information on the allosteric regulation of higher plant ADP-glucose pyrophosphorylases and validates a strategy for developing novel variants of the enzyme that may be useful in manipulating starch biosynthesis in higher plants.
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PMID:Generation of up-regulated allosteric variants of potato ADP-glucose pyrophosphorylase by reversion genetics. 970 46

Comparison has been made of a simple method originated by Absolon and modified in our laboratories for assay of proteolytic activity using RISA (radioactive iodinated serum albumin-Abbott Laboratories), with the commonly used photometric methods of Anson and Kunitz. In this method, pepsin was incubated with an albumin substrate containing RISA, followed by precipitation of the undigested substrate with trichloroacetic acid and measurement of radioactive digestion products in the supernatant fluid. The I(131)-albumin bond was shown in the present studies to be altered only by the proteolytic activity, and not by the incubation procedures at various values of pH. Any free iodine present originally in the RISA was removed by a single passage through a resin column (amberlite IRA-400-C1). Pepsin was shown to be most stable in solution at a pH of 5.5. Activity of pepsin was shown to be maximal when it was incubated with albumin at a pH of 2.5. Pepsin activity was shown to be altered in the presence of various electrolytes. Pepsin activity measured by the RISA and Anson methods as a function of concentration or of time of incubation indicated that these two methods are in good agreement and are equally sensitive. Consistently smaller standard errors were obtained by the RISA method of pepsin assay than were obtained with either of the other methods.
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PMID:Comparative studies of three methods for measuring pepsin activity. 1358 10

The following experimental results have been obtained. 1. Native egg albumin treated with iodine and then denatured no longer gives a nitroprusside test or reduces dilute ferricyanide in neutral Duponol PC solution. 2. More iodine is needed to abolish the ferricyanide reduction if the reaction between native egg albumin and iodine is carried out at pH 6.8 than if the reaction is carried out at pH 3.2. At pH 6.8 iodine reacts with tyrosine as well as with cysteine. 3. Cysteine and tryptophane are the only amino acids with reducing groups which are known to react with dilute iodine at pH 3.2 The reducing power of cysteine is abolished by the reaction with iodine, whereas the reducing power of tryptophane remains intact. Pepsin and chymotrypsinogen which contain tryptophane but not cysteine, do not react at all with dilute iodine at pH 3.2. 4. Native egg albumin treated with iodoacetamide at pH 9.0 and then denatured by Duponol PC reduces only 60 per cent as much dilute ferricyanide as egg albumin which has not been treated with iodoacetamide. 5. The SH group is the only protein reducing group which is known to react with iodoacetamide. The simplest explanation of the new observation that the SH groups of egg albumin can be modified by reactions with the native form of the protein is that the native egg albumin has free and accessible but relatively unreactive SH groups which can react with iodine and iodoacetamide despite the fact that they do not react with ferricyanide, porphyrindin, or nitroprusside. Preliminary experiments suggested by the results with egg albumin indicate that the tobacco mosaic virus is modified by iodine at pH 2.8 without being inactivated and that the tobacco mosaic and rabbit papilloma viruses are not inactivated by iodoacetamide at pH 8.0.
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PMID:THE REACTIONS OF IODINE AND IODOACETAMIDE WITH NATIVE EGG ALBUMIN. 1987 58

1. Pepsin solutions were iodinated at pH 5.0-6.0 until 10-20 per cent of the activity was lost and 1/20 (0.7 per cent) of the saturating amount of iodine had been introduced into the protein molecule. After alkaline hydrolysis 65 per cent of the original iodine was accounted for as mono-iodotyrosine although only 42 per cent was isolated as a crystalline product. No evidence was obtained to support the possibility that any group other than tyrosine in pepsin was iodinated. 2. Some of the properties of the crystalline l-mono-iodotyrosine were determined and compared to those of di-iodotyrosine. 3. One iodinated pepsin preparation was crystallized. The crystal form was the same as that of the original pepsin. A solubility curve of the crystals demonstrated that it was very different from pepsin and had nearly constant solubility.
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PMID:INACTIVATION OF PEPSIN BY IODINE : II. ISOLATION OF CRYSTALLINEl-MONO-IODOTYROSINE FROM PARTIALLY IODINATED PEPSIN. 1987 64