Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0272170 (SDS)
 50,377 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To identify potential tissue-specific characteristics of intestinal glycoprotein synthesis and processing, rat intestinal lactase-phlorizin hydrolase (L-Ph) was studied after pulse-labeling of colonic explants from 5-d-old suckling rats in organ culture and the data compared to similar studies in rat jejunum. Histologic sections of 5-d-old proximal colon showed villus-like structures lined with columnar epithelial cells. Lactase and phlorizin hydrolase activities showed tissue-specific developmental patterns. Using a MAb to small intestinal L-Ph, we were able to immunoprecipitate from colon at different ages a protein that hydrolyzed lactose and phlorizin, and whose activity was not inhibited by p-chloromercuribenzoate. After pulse-labeling for 60 min and chase for 30 min, immunoprecipitated L-Ph from total homogenates of rat colonic explants appeared on fluorography of SDS-PAGE as one band of approximately 205 kD. With increasing time of chase, it took 240 min before the precursor form was converted to the intermediate form (equivalent to the 180-kD form in jejunum) and the mature form (equivalent to the 130-kD form in jejunum), although these conversions in the jejunum were observed within 60 min of chase, and only 30 min of pulse labeling. When compared on SDS-PAGE to immunoprecipitated jejunal L-Ph, the precursor form in the colon had a slightly higher apparent mol wt than the corresponding precursor form found in the endoplasmic reticulum-Golgi fraction of the jejunum. The intermediate as well as the mature L-Ph forms in the colon were also both somewhat higher in apparent molecular weight than the same bands in the microvillus membrane fraction from jejunal explants. Removal of N-linked oligosaccharides from jejunum and colonic forms of L-Ph produced bands on SDS-PAGE with identical mobility, suggesting that the proteins were the same. The data demonstrate that, in neonatal colon, enzymatically active L-Ph undergoes biosynthetic and processing events similar to those in the jejunum. During early life, colonic L-Ph may function in the salvage of lactose not absorbed in the small intestine.
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PMID:Suckling rat colon synthesizes and processes active lactase-phlorizin hydrolase immunologically identical to that from jejunum. 251 43

In this paper we provide evidence that ectoplasmic specializations are a form of intercellular adhesion junction. Ectoplasmic specializations, found at basal junctions between adjacent Sertoli cells and at sites of adhesion between Sertoli cells and germ cells, consist of actin filament bundles sandwiched between the plasma membrane and a cistern of endoplasmic reticulum. The actin filaments in each bundle are unipolar and are hexagonally packed. The bundles are coupled to the adjacent membranes and to each other. Because ectoplasmic specializations are associated with junctional sites, they may play a role in intercellular adhesion. In this study, we report a procedure for obtaining samples enriched for ectoplasmic specializations and identify polypeptides that may be associated with ectoplasmic specializations. On SDS-polyacrylamide gels, an 83K (K = 10(3) Mr) polypeptide is specific to the ectoplasmic specialization-enriched sample, suggesting that it may be a component of ectoplasmic specializations. Other polypeptides at 38, 53, 56 and 69K also may be associated with ectoplasmic specializations. Immunoblots further indicate that fimbrin and vinculin are present in the ectoplasmic specialization-enriched fraction. In addition, immunofluorescence indicates that vinculin is associated with spermatid-Sertoli cell and Sertoli-Sertoli cell junctions. We suspect that fimbrin, an actin-bundling protein, may be involved in cross-linking the hexagonally packed actin filaments in ectoplasmic specializations while vinculin may be associated with actin-membrane linkages. If so, ectoplasmic specializations may be a new class of actin-associated junctional site. Moreover, the presence of vinculin in testicular fractions enriched for ectoplasmic specializations and at junctional sites supports the view that these structures may play a role in intercellular adhesion, possibly by stabilizing an adhesive membrane domain.
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PMID:Sertoli cell ectoplasmic specializations: a type of actin-associated adhesion junction? 251 96

Rat retinas were labeled either by intravitreal injection of [14C]leucine or by incubation with [3H]-leucine or [35S]-methionine. Subcellular fractions were prepared on linear sucrose gradients and rhodopsin was extracted with detergent and purified by chromatography on ConA-Sepharose. A fraction enriched in rough endoplasmic reticulum (RER) and substantially free of rod outer segments (ROS) was found to contain a light-sensitive protein exhibiting the properties of rhodopsin on ConA-Sepharose or Agarose chromatography and on SDS-polyacrylamide gel electrophoresis, as well as immunologically. Intravitreal injection of [3H]-retinol also labeled the rhodopsin in the RER under conditions in which the rhodopsin in the ROS was not heavily labeled. Thus the chromophore appears to be attached to opsin shortly after the apoprotein is translated in the RER.
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PMID:Addition of the chromophore to rat rhodopsin is an early post-translational event. 252 80

The pathogenesis of coeliac disease has been investigated by studying the response of small intestinal hydrolases in patients with coeliac disease subject to gluten challenge. Small intestinal biopsies taken before and two and a half hours after a gluten challenge in five patients with coeliac disease who had been maintained on a gluten free diet were examined by a combination of electron and light microscopy, organ culture, pulse chase biosynthetic labelling, SDS-PAGE and autoradiography. Before the challenge, the small intestinal biopsies showed nearly normal morphology. Two and a half hours after the challenge there was deterioration in villus architecture, distortion of microvillus structure, disorganisation of the intermicrovillus pit region, an increase in lysosome like bodies in the apical cytoplasm of the luminal enterocytes and pronounced hypertrophy of the rough endoplasmic reticulum of these cells. SDS-PAGE of small intestinal biopsies from four treated coeliac patients before gluten challenge revealed normal microvillus membrane and hydrolase composition. There was a generalised reduction but no specific alteration in the pattern of polypeptide synthesis in the mucosa of the small intestine in these subjects two and a half hours after the gluten challenge. These results suggest that the generalised reduction in small intestinal brush border enzymes in coeliac patients is not the primary pathogenetic mechanism and represents a secondary effect.
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PMID:Early biochemical responses of the small intestine of coeliac patients to wheat gluten. 256 83

The path and synchrony of intracellular transport of 12 secretory proteins of the guinea pig exocrine pancreas have been studied in pulse-chase amino acid labeling experiments by quantitative analysis of the individual proteins recovered in subcellular fractions and extracellular samples. Protein fractionation was accomplished by two-dimensional isoelectric focusing/SDS-gel electrophoresis. Use of a double-label protocol allowed correction of the data on a protein-by-protein basis for leakage and adsorption artifacts which accompany tissue homogenization. All the labeled secretory (pro)enzymes, including their isoenzymic forms, were recovered in rough microsomal, Golgi-enriched and granule fractions during their transport to the cell surface. However, major asynchrony was observed at four levels: exit from the rough endoplasmic reticulum; transit through the Golgi complex; entry into granules; and discharge from the cell. Rapid transport rates were observed for trypsinogen, chymotrypsinogen 2, procarboxypeptidase A2, and lipase 2. Slow transport rates were observed for amylase and procarboxypeptidase B. In the presence of carbamylcholine or cholecystokinin stimulation, the times required for 40% discharge of labeled chymotrypsinogen 2, trypsinogen, amylase, and procarboxypeptidase B were 98, 102, 148, and 180 min, respectively. Transport rates did not correlate with isoelectric point, molecular weight, or the presence of carbohydrate. These data suggest that interactions occur within the rough endoplasmic reticulum, either between secretory (nonglyco)-proteins themselves or between such proteins and the cisternal face of the rough endoplasmic reticulum.
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PMID:Exit of nonglycosylated secretory proteins from the rough endoplasmic reticulum is asynchronous in the exocrine pancreas. 257 56

Seven subjects belonging to three families (ME, MA, MO), with congenital goiter and various degrees of thyroid hypofunction, were investigated from the standpoints of clinical, biochemical, and molecular biology. In two of these families (ME, MA), 6 individuals had low serum levels of Tg-related antigens with a minor increase after bovine TSH (bTSH) stimulation. A large proportion of the tracer was incorporated into serum albumin, and Tg antigens in the thyroid extracts were barely detectable by RIA. (0.19 mg/g tissue; normal, 70-90 mg/g). Gel filtration (CL6B Sepharose gel) showed absence of a normal Tg peak, and SDS agarose gel electrophoresis indicated complete absence of Tg dimer and monomer. Immunoelectrophoresis confirmed the absence of Tg-related antigens. Thus, in these patients a quantitative defect of Tg gene expression was characterized. By contrast, in the MO family a high basal serum concentration of immunoreactive Tg was present, with an exaggerated response to bTSH. Thyroid extracts revealed elevated TPO activity and normal levels of Tg-related antigens. Tg was also eluted in the gel filtration columns with the same mobility as standard 19S Tg. Immunoelectrophoresis against rabbit and human Tg was abnormal, with two precipitin arcs being detected. The Tg molecule after hydrolysis yielded only DIT and MIT, with poor formation of iodothyronines. Microscopic studies revealed a pronounced lack of colloid in the follicular lumina, and overdistended endoplasmic reticulum cisternae.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Qualitative and quantitative defects of thyroglobulin resulting in congenital goiter. Absence of gross gene deletion of coding sequences in the TG gene structure. 261 17

The enzyme GDP mannose:dolichyl-phosphate O-beta-D-mannosyltransferase (GDP-Man:DolP mannosyltransferase) catalyzing the reaction: GDP-man + DolP in equilibrium DolP-Man + GDP has been purified from Saccharomyces cerevisiae to homogeneity. The purification was achieved using a combination of column chromatographic methods with preparative gel electrophoresis. The enzyme has an apparent molecular mass of 30 kDa on SDS/polyacrylamide gels. Enzymatic activity could be correlated directly with this band. Antibodies against the transferase were raised in rabbits. The immune serum obtained removed enzymatic activity from a detergent extract of yeast membranes and reacted specifically with the 30-kDa band on immunoblots. Experiments addressing the orientation of this enzyme in the endoplasmic reticulum membrane are presented by using selective trypsin and N-ethylmaleimide treatment.
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PMID:Purification of GDP mannose:dolichyl-phosphate O-beta-D-mannosyltransferase from Saccharomyces cerevisiae. 265 45

Apoprotein part of tissue factor of human placenta was purified 871 fold from the starting material with 4.2% yield by concanavalin A-Sepharose affinity chromatography and SDS-PAGE. The molecular weight of purified apoprotein was 45,000 in non-reduced condition and 49,000 in reduced condition. Tissue factor of human leukemia cells (FAB classification:M2 and M3) and cultured leukemia cell lines (HL-60 and Molt-4) was analyzed using specific rabbit anti-tissue factor IgG raised against purified material. Endotoxin stimulated HL-60 and Molt-4 also expressed procoagulant activity which was inhibited by tissue factor immune IgG. By immunostaining of the purified material, the lysate of leukemia cells (M2 and M3) and cultured leukemia cells (HL-60 and MOLT-4) revealed a major band of the same apparent molecular weight. Immuno-electron microscopic study on tissue factor of HL-60 cells produced the following findings: stimulation by endotoxin resulted in the formation of pseudopods of the cell membrane, and immunogold particles accumulated mainly on these pseudopods and cisternal spaces of rough endoplasmic reticulum, indicating exposure of the tissue factor to the surface of perturbed cell membrane with concurrent increase in tissue factor synthesis.
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PMID:Studies on leukemic cell tissue factor. 266 Mar 21

Human peripheral blood monocytes (Mo) synthesize prostaglandin E2 (PGE2) when activated with lipopolysaccharide (LPS). This production is strongly enhanced by the addition of supernatant from phytohaemagglutinin (PHA)-activated T cells. To evaluate the factor(s) responsible for this enhancement we studied the effect of several cytokines on the PGE2 metabolism. Recombinant interleukin-1 (IL-1) or recombinant IL-2 strongly enhanced PGE2 synthesis in LPS-stimulated Mo cultures, whereas recombinant interferon-gamma (IFN-gamma) partially inhibited its production. To see whether the effect of IL-2 on Mo was due to the presence of IL-2 receptor (IL-2R) on the cell surface, flow cytometric analysis and electron microscopy were used to investigate IL-2R expression in unstimulated and stimulated Mo. Stimulated, but not resting, Mo displayed the p55 IL-2R chain on their cellular surface and associated with the polyribosomes of the rough endoplasmic reticulum in the cytoplasm. This finding strongly suggested that the p55 chain of the IL-2R was synthesized by activated Mo. To confirm this result, 125I-labelled IL-2 was bound under high- and low-affinity conditions and cross-linked to Mo cultured in the presence of LPS, IFN-gamma or IL-1. The cross-linked 125I-IL-2/IL-2R complexes were analysed by SDS-PAGE. Mo cultured with LPS, IFN-gamma and IL-1 expressed the p55 protein detected by low-affinity cross-linking, whereas only LPS-stimulated Mo displayed a barely detectable band with an apparent MW of 70,000 under high-affinity binding conditions. In addition, stimulated Mo were found capable of producing the soluble form of IL-2R. Finally, LPS-activated Mo only responded to the addition of IL-2 by an increase in PGE2 production, suggesting that the function of IL-2R on activated Mo is linked to the stimulus applied.
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PMID:The expression of functional IL-2 receptor on activated macrophages depends on the stimulus applied. 266 16

A ketone reducing enzyme was purified to homogeneity from female mouse liver microsomes, using the diagnostic cytochrome P-450 inhibitor metyrapone as a substrate. In contrast to the usually employed indirect spectrophotometric recording of pyridine nucleotide oxidation at 340 nm, a HPLC method was applied for direct alcohol metabolite determination. Purification of the carbonyl reductase resulted in a 360-fold increase in specific activity together with a single band in the 34 kD region after SDS-polyacrylamide gel electrophoresis. Phenobarbital, indomethacin, dicoumarol and 5 alpha-dihydrotestosterone inhibited the enzyme, whereas quercitrin did not affect the enzyme activity. Thus, by inhibitor classification of carbonyl reductases the ketone metyrapone is reduced by an aldehyde reductase, rather than by a ketone reductase. Dihydrotestosterone, the strongest inhibitor, is supposed to be the physiological substrate for the purified enzyme. It was demonstrated that during the steps of purification both NADPH and NADH can supply the required reducing equivalents, although the activity with NADH is weaker. The highest activity was obtained using an NADPH-regenerating system. Ethanol and the nonionic detergent Emulgen 913 led to an increased specific activity, indicating that the enzyme is bound to the membranes of the endoplasmic reticulum in a latent state. From these results it is concluded that the microsomal metyrapone-reducing enzyme belongs to the family of carbonyl reductases, but differs from the common patterns of their classification with regard to cofactor requirement and inhibitor susceptibility.
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PMID:Purification and properties of a metyrapone-reducing enzyme from mouse liver microsomes--this ketone is reduced by an aldehyde reductase. 267 47


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