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

The steroid-binding capacity of the adrenocortical pregnenolone-binding protein (PBP) is effectively destroyed by extreme temperature (boiling water for 2-5 min); however, the boiled preparation contains a factor that potentiates ligand binding when readded to native PBP. Treatment of the boiled fraction with calf intestinal alkaline phosphatase at pH 9 reverses the stimulatory effect on PBP activity. Additionally, if native PBP is first incubated with alkaline phosphatase, which converts it to a nonbinding form, activity can be fully restored in a dose-dependent manner by the addition of the boiled preparation. The factor (itself devoid of binding capacity) can also be generated by exposing native PBP to acidic conditions (pH 4). The molecule is small (mol wt, less than 2000), as judged by Sephadex G-25 gel filtration and equilibrium dialysis. It is not retained on Concanavalin-A-Sepharose and is not extractable with a variety of organic solvents. The factor remains active after lyophilization and has a net negative charge at pH 7.4 (determined by DEAE-cellulose chromatography). While the binding capacity of native PBP is destroyed by a variety of proteases, the heat-stable factor is unaffected by similar treatment. Additionally, factor activity is not susceptible to RNase, DNase, or lipase digestion. Thus, the protein moiety of the PBP has an absolute requirement for a distinct phosphorylated heat-stable factor for expression of ligand-binding activity, and it may be through this factor that binding activity is regulated. It is not yet known whether the factor is acting allosterically or actually functions as part of the steroid-binding site.
Mol Endocrinol 1991 Sep
PMID:Adrenocortical pregnenolone-binding protein activity requires a small heat-stable factor: evidence that regulation by phosphorylation/dephosphorylation occurs at the level of the factor, not the protein. 177 Sep 49

The neutral lipase from the bacteria Pseudomonas fluorescens, marketed under the trade name LpL-200S, has been crystallized in a form suitable for X-ray diffraction analysis from 35% n-propanol at pH 8.5. The crystals are monoclinic prisms and are of space group C2 with a = 91.00 A, b = 47.17 A, c = 35.21 A and beta = 121.43 degrees. There is one molecule of the protein as the asymmetric unit of the crystals. The diffraction pattern extends to at least 1.6 A resolution and the crystals are extremely robust in terms of X-ray exposure.
J Mol Biol 1991 Nov 05
PMID:Preliminary investigation of crystals of the neutral lipase from Pseudomonas fluorescens. 194 65

Energy metabolism in spermatozoa of the sea urchin Glyptocidaris crenularis was examined. The spermatozoa contained not only several kinds of phospholipids and cholesterol but also triacylglycerides (TG). Following dilution of the dry sperm in sea water, the TG content decreased rapidly. Other lipids, however, remained at constant levels, except for an increase in the level of free fatty acid. Oil red-O staining of spermatozoa showed that TG was principally located in part of the sperm midpiece. Also, high lipase activity was demonstrated in the spermatozoa. In both intact cells and a cell-free system, 14C-labeled fatty acids were oxidized to 14CO2. It is thus concluded that G. crenularis spermatozoa use TG as a substrate for energy metabolism.
Mol Reprod Dev 1991 Mar
PMID:Energy metabolism of spermatozoa of the sea urchin Glyptocidaris crenularis. 201 87

Rabbit aortic smooth muscle cells take up lipid droplets when they are presented using an inverted culture technique. These droplets were localized in secondary lysosomes as demonstrated by staining for acid phosphatase. Initially, 69% of the cell volume was occupied by lipid, and 94% of the lipid was in lysosomes. After a 24-hr clearance period, the cell volume occupied by lipid decreased to 53%, although there was no change in the fraction of cell lipid that was in lysosomes. To confirm that hydrolysis of droplet lipid was occurring in lysosomes, cultures were exposed to medium containing Sandoz 58-035, an inhibitor of acyl CoA:cholesterol acyl transferase, for 24 hr in the presence and absence of chloroquine, ammonium chloride, or methylamine. Although the hydrolysis of cholesteryl oleate was sensitive to these lysosomotropic agents, the hydrolysis of triolein was not. Using reconstituted LDL containing cholesteryl oleate and triolein, we demonstrated that the hydrolyses of cholesteryl oleate and triolein were equally sensitive to the lysosomotropic agents when the cells were not loaded with droplet lipid. However, in cells loaded with lipid, hydrolysis of LDL cholesteryl ester was sensitive to the lysosomotropic agents but hydrolysis of triolein was not. We therefore conclude that both droplet lipids were hydrolyzed in lysosomes, and we attribute the failure of the lysosomotropic agents to inhibit fully the hydrolysis of droplet triolein to the presence of a large mass of free fatty acids in the lysosome that maintains a sufficiently low pH to sustain the triglyceridase activity, but not the cholesteryl esterase activity, of the lysosomal acid lipase.
Exp Mol Pathol 1991 Apr
PMID:Lysosomal hydrolysis of lipids in a cell culture model of smooth muscle foam cells. 202 36

U-57 908 (RHC 80267) inhibited diacylglycerol (DG) lipase activity in soluble and microsomal subcellular fractions from cardiac myocytes isolated from adult rat hearts; half-maximal inhibition was observed at a concentration of 3.5 microM. Monoacylglycerol lipase activity was much less sensitive to inhibition, but U-57 908 reduced lipoprotein lipase activity in cardiac myocytes with the same sensitivity as observed for DG lipase. DG kinase activity was not inhibited by U-57 908. DG metabolism by intact cardiac myocytes was studied in incubations with a cell-permeable DG analog, [3H]-dioctanoylglycerol (diC8). DiC8 was mainly metabolized by conversion to mono-octanoylglycerol (monoC8) and glycerol (lipase pathway); much less radioactivity was incorporated into the triacylglycerol and total phospholipid fractions. U-57 908 reduced the loss of radioactivity from the exogenous diC8 substrate, with a corresponding decline in the formation of radiolabelled monoC8 and glycerol. The incorporation of radioactivity into phospholipids was slightly reduced, but triacylglycerol synthesis from diC8 was increased in the presence of U-57 908. Therefore, U-57 908 is an effective inhibitor of DG metabolism by the lipase pathway in intact cardiac myocytes.
J Mol Cell Cardiol 1990 Sep
PMID:Inhibition of diacylglycerol metabolism in isolated cardiac myocytes by U-57 908 (RHC 80267), a diacylglycerol lipase inhibitor. 217 92

We have shown earlier that the 12-lipoxygenase product of arachidonic acid (AA), 12-hydroxyeicosatetraenoic acid (12-HETE), plays an important role in mediating angiotensin II (AII)-induced aldosterone secretion (J. Clin. Invest. (1987) 80, 1763). In the present study, we have evaluated whether diacylglycerol (DG) is the source of arachidonic acid giving rise to this 12-HETE. Treatment of rat adrenal glomerulosa cells with a DG lipase inhibitor, RHC 80267, which prevents conversion of DG to AA and HETEs, blocked AII-induced aldosterone and 12-HETE formation. In contrast, a DG kinase inhibitor, R59022, which prevents conversion of DG to phosphatidic acid, potentiated AII-induced aldosterone and 12-HETE formation. These two inhibitors block DG metabolism which would be expected to lead to increased DG levels and protein kinase C activity and AII-induced steroidogenesis. However, only R59022 potentiated AII action while RHC 80267 was inhibitory. This suggests that conversion of DG to AA and 12-HETE is important for AII action. Further proof for this was obtained by measuring [3H]AA-labeled DG levels. The combination of the inhibitors significantly potentiated AII-induced DG formation even though this same combination was inhibitory on AII-induced aldosterone and 12-HETE. Thus, the inhibitory effect of RHC 80267 is due to blockade of AA release and not of DG formation. These results suggest that DG plays a dual role in AII action, both as an activator of protein kinase C and as a source of AA for 12-HETE formation.
Mol Cell Endocrinol 1990 Aug 20
PMID:Key role of diacylglycerol-mediated 12-lipoxygenase product formation in angiotensin II-induced aldosterone synthesis. 217 2

A number of proteins in Eimeria tenella are shown to possess a carbohydrate similar to that found on the carboxyl terminus of the variant surface glycoprotein from Trypanosoma brucei. In trypanosomes, this carbohydrate is part of a glycolipid structure responsible for membrane attachment. In common with the variant surface glycoprotein and with other glycolipid linked proteins, the E. tenella proteins were shown to be hydrophobic. Treatment with a crude lipase preparation from T. brucei modifies these proteins to a water-soluble form.
Mol Biochem Parasitol 1990 Jun
PMID:A family of glycolipid linked proteins in Eimeria tenella. 220 29

The effect of a reduction in protein kinase C activity on the metabolism of exogenous [3H]diC8 by freshly isolated smooth muscle cells from rabbit aorta and cultured A10 smooth muscle cells was determined. The metabolism of [3H]diC8 by both smooth muscle cell preparations was predominantly by hydrolysis to yield monoC8 and glycerol (lipase pathway); very little radioactivity was incorporated into phospholipids. Diacylglycerol lipase activity measured in vitro with A10 cell homogenates was much greater than diacylglycerol kinase activity. The addition of the protein kinase C inhibitor H-7 to incubations of isolated aortic smooth muscle cells and cultured A10 cells had no significant effect on the metabolism of [3H]diC8. Protein kinase C activity in cultured A10 cells preincubated for 20 h with a phorbol ester was reduced to 14% of control as a consequence of down-regulation, but diC8 metabolism was not changed. Therefore, protein kinase C does not regulate the metabolism of diacylglycerols in aortic smooth muscle cells.
Mol Cell Biochem 1990 Jul 17
PMID:Protein kinase C does not regulate diacylglycerol metabolism in aortic smooth muscle cells. 223 6

Isolated rat hearts were perfused with various external Ca2+ concentrations and with various Ca2+ uptake antagonists. Compared to control activities (at 1.2 mM Ca2+), 0.6 mM Ca2+ and Ca2+ antagonists inhibited triglyceride lipase (TGL) and stimulated glycerol 3-phosphate acyltransferase (GPAT). Raising external Ca2+ concentration above the control value had no effect on TGL activity but GPAT activity was greatly reduced. Therefore, it appears that GPAT, but not TGL, will respond to increases in [Ca2+]. During ischaemia the activity of TGL is increased and that of GPAT is inhibited by beta-adrenergic activation. On reperfusion, TGL activity returns to pre-ischaemic values but GPAT activity is further reduced. In this study pre-perfusion of hearts with the Ca2+ antagonist diltiazem (10(-6) M) produced the following effects on enzyme activity during ischaemia and reperfusion: after 10 min ischaemia, TGL activity was increased and GPAT activity decreased to the same extent as seen during ischaemia in control hearts; however, on reperfusion of diltiazem-perfused hearts, the activities of both TGL and GPAT returned to pre-ischaemic values. These results suggest that Ca2+ entry on reperfusion is responsible for the reperfusion-induced decrease in GPAT activity.
J Mol Cell Cardiol 1990 Mar
PMID:The effect of calcium antagonists on the activities of lipid metabolizing enzymes in the isolated ischaemically perfused and reperfused rat heart. 235 98

Intraperitoneal injection of lysine (400 mg/100 g body weight) in rats caused necrosis of pancreatic acinar cells with fat necrosis and a significant increase in serum amylase and lipase. The early morphological changes in the pancreas were investigated. At 3 to 6 h, marked swelling of mitochondria was observed throughout the cytoplasm followed later by dilation of the endoplasmic reticulum and the formation of autophagic vacuoles, indicative of rapid cellular degeneration. These results suggest that transient disturbance of energy formation following mitochondrial swelling resulted in disorders of protein metabolism, with disorganization of the endoplasmic reticulum and pyknosis of the nuclei as later events.
Virchows Arch B Cell Pathol Incl Mol Pathol 1985
PMID:Pancreatic damage produced by injecting excess lysine in rats. 241 6


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