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

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on deoxyuridine 5'-triphosphatase (dUTPase) in the cytosol of rat liver was investigated. Addition of Ca2+ up to 5.0 microM to the enzyme reaction mixture caused a significant decrease of dUTPase activity, while Zn2+, Cd2+, Co2+, Al3+, Mn2+ and Ni2+ (10 microM) did not have an appreciable effect. The Ca(2+)-induced decrease of dUTPase activity was reversed by the presence of regucalcin; the effect was complete at 1.0 microM of the protein. Regucalcin had no effect on the basal activity of the enzyme. Meanwhile, the reversible effect of regucalcin on the Ca2+ (10 microM)-induced decrease of dUTPase activity was not altered by the coexistence of Cd2+ or Zn2+ (10 microM). The present data suggest that liver cytosolic dUTPase is uniquely regulated by Ca2+ of various metals, and that the Ca2+ effect is reversed by regucalcin.
Mol Cell Biochem 1992 Mar 04
PMID:Reversible effect of calcium-binding protein regucalcin on the Ca(2+)-induced inhibition of deoxyuridine 5'-triphosphatase activity in rat liver cytosol. 131 24

The effect of regucalcin, isolated from rat liver cytosol, on neutral proteolytic activity in the hepatic cytosol was investigated. The Ca(2+)-requiring proteinase required 5-10 microM Ca2+ for maximal activity in the presence of a protein substrate (globin). The proteinase activity was markedly elevated by the addition of regucalcin (0.25-2.0 microM) in the absence or presence of Ca2+ (5.0 microM) added. The effect of regucalcin, however, was the greater in the absence of Ca2+ than that in the presence. The pronounced effect of regucalcin on the proteinase activity was also seen in the presence of 1.0 mM EGTA with or without Ca2+ (5.0 microM). In the absence of Ca2+, the regucalcin-increased proteinase activity was clearly inhibited by the presence of anti-regucalcin antiserum (diluted to 240-fold), leupeptin (20 and 200 micrograms/ml), and heavy metals (25 microM cadmium or 25 microM zinc), although the inhibition was not complete at the concentration used. The present findings suggest that regucalcin increases proteolytic activity in rat liver cytosol, and that regucalcin may activate Ca(2+)-independent neutral cysteinyl-proteinase.
Mol Cell Biochem 1992 May 13
PMID:Calcium-binding protein regucalcin increases calcium-independent proteolytic activity in rat liver cytosol. 151 38

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+ transport in rat liver nuclei was investigated. Ca2+ uptake and release were determined with a Ca2+ electrode. Ca2+ uptake increased dependent on adenosine triphosphate (ATP; 0.5-2.0 mM), while the uptake was negligible in the presence of 2 mM ADP or AMP. Regucalcin (0.5-2.0 microM) had no effect on Ca2+ uptake following addition of 2.0 mM ATP. Meanwhile, Ca2+, which accumulated in the nuclei during 10 min after ATP addition, was significantly released by the addition of regucalcin. This release was dose-dependent (0.1-2.0 microM). Vanadate (100 microM) and guanosine triphosphate (100 microM) did not cause a significant release of Ca2+ from the nuclei. Trifluoroperazine (TFP; 50 microM), an antagonist of calmodulin, significantly increased Ca2+ release from the nuclei. The presence of regucalcin (0.5 microM) further enhanced the TFP effect. These results indicate that regucalcin stimulates Ca2+ release from liver nuclei, and that the effect is not influenced by calmodulin antagonist. The finding suggests that regucalcin can regulate the Ca2+ transport system in rat liver nuclei.
Mol Cell Biochem 1992 Jul 06
PMID:Effect of calcium-binding protein regucalcin on Ca2+ transport system in rat liver nuclei: stimulation of Ca2+ release. 164 Sep 37

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on Ca2+/calmodulin-dependent cyclic nucleotide (AMP) phosphodiesterase activity in rat liver cytosol was investigated. The addition of Ca2+ (50 microM) and calmodulin 160 U/ml in the enzyme reaction mixture caused a significant increase in cyclic AMP phosphodiesterase activity. This increase was inhibited by the presence of regucalcin (0.5-3.0 microM); the inhibitory effect was complete at 1.0 microM. Regucalcin (1.0 microM) did not have an appreciable effect on basal activity without Ca2+ and calmodulin. The inhibitory effect of regucalcin was still evident even at several fold higher concentrations of calmodulin (160-480 U/ml). However, regucalcin (1.0 microM) did not inhibit Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity in the presence of 100 and 200 microM Ca2+ added. Meanwhile, Cd2+ (25-100 microM)-induced decrease in Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity was not reversed by the presence of regucalcin (1.0 microM). The present results suggest that regucalcin can regulate Ca2+/calmodulin-dependent cyclic AMP phosphodiesterase activity due to binding Ca2+ in liver cells.
Mol Cell Biochem 1991 Jul 24
PMID:Inhibitory effect of calcium-binding protein regucalcin on Ca2+/calmodulin-dependent cyclic nucleotide phosphodiesterase activity in rat liver cytosol. 165 6

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on in vitro protein synthesis in the 5500 g supernatant fraction of rat liver homogenate was investigated. Addition of Ca2+ up to 5.0 microM in the reaction mixture caused a significant decrease in protein synthesis. This decrease was saturated at 10 microM Ca2+. The Ca2+ effect was not reversed by the presence of regucalcin (2.0 microM); the protein caused a remarkable decrease in hepatic protein synthesis, and it enhanced significantly the Ca2+ effect. Meanwhile, calmodulin (2.5-20 micrograms/ml), a calcium-binding protein, did not have an appreciable effect on the Ca2+ (10 microM)-induced decrease in hepatic protein synthesis. [3H]Leucyl-tRNA synthetase activity in the 105000 g supernatant fraction (cytosol) of liver homogenate was markedly decreased by addition of Ca2+ (1.0-50 microM). This decrease was not reversed by the presence of regucalcin (2.0 microM); the protein (1.0-2.0 microM) caused a remarkable decrease in the enzyme activity. The present results suggest that regucalcin can regulate protein synthesis in liver cells.
Mol Cell Biochem 1990 Dec 03
PMID:Effect of calcium-binding protein regucalcin on hepatic protein synthesis: inhibition of aminoacyl-tRNA synthetase activity. 228 Jul 66

The increasing effect of regucalcin, isolated from rat liver cytosol, on neutral proteolytic activity in the hepatic cytosol was characterized. The proteolytic activity was markedly elevated by the addition of regucalcin (0.1-0.5 microM) in the absence of Ca2+. This increase was not significantly altered by the presence of diisopropylfluorophosphate (DPF; 2.5 mM)--although DFP caused a significant decrease in the proteolytic activity. Regucalcin (0.25 microM) additively enhanced the dithiothreitol (DTT; 1.0 mM)--increased proteolytic activity, while the regucalcin or DTT effect was completely abolished by NEM (5 mM), indicating that regucalcin may act on the SH group in proteases. Also, regucalcin (0.25 microM) enhanced the effect of Ca2+ (10 microM) increasing liver proteolytic activity, suggesting that regucalcin does not influence on the active sites for Ca2+ in proteases. Moreover, the proteolytic activity of regucalcin (0.25 microM) was significantly decreased by the presence of calpastatin (24 micrograms/ml), an inhibitor of Ca(2+)-activated neutral protease (calpain). Now, regucalcin (0.25 microM) increased about 7-fold the activity of m-calpain isolated from rabbit skeletal muscle. These observations demonstrate that regucalcin directly activates cysteinyl-proteases. Regucalcin may have a role as a potent proteolytic activator in the cytoplasm of liver cells.
Mol Cell Biochem 1995 Jul 05
PMID:Characterization of regucalcin effect on proteolytic activity in rat liver cytosol: relation to cysteinyl-proteases. 747 35

The yeast Sen1 protein was discovered by virtue of its role in tRNA splicing in vitro. To help determine the role of Sen1 in vivo, we attempted to overexpress the protein in yeast cells. However, cells with a high-copy SEN1-bearing plasmid, although expressing elevated amounts of SEN1 mRNA, show little increase in the level of the encoded protein, indicating that a posttranscriptional mechanism limits SEN1 expression. This control depends on an amino-terminal element of Sen1. Using a genetic selection for mutants with increased expression of Sen1-derived fusion proteins, we identified mutations in a novel gene, designated SEN3. SEN3 is essential and encodes a 945-residue protein with sequence similarity to a subunit of an activator of the 20S proteasome from bovine erythrocytes, called PA700. Earlier work indicated that the 20S proteasome associates with a multisubunit regulatory factor, resulting in a 26S proteasome complex that degrades substrates of the ubiquitin system. Mutant sen3-1 cells have severe defects in the degradation of such substrates and accumulate ubiquitin-protein conjugates. Most importantly, we show biochemically that Sen3 is a subunit of the 26S proteasome. These data provide evidence for the involvement of the 26S proteasome in the degradation of ubiquitinated proteins in vivo and for a close relationship between PA700 and the regulatory complexes within the 26S proteasome, and they directly demonstrate that Sen3 is a component of the yeast 26S proteasome.
Mol Cell Biol 1995 Nov
PMID:The yeast SEN3 gene encodes a regulatory subunit of the 26S proteasome complex required for ubiquitin-dependent protein degradation in vivo. 756 84

The effect of nuclear receptor-related hormones on the expression of hepatic calcium-binding protein regucalcin mRNA in rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin cDNA (0.9 kb of open-reading frame). A single subcutaneons administration of 17 beta-estradiol (0.5, 1.0 and 2.0 mg/kg body weight) in rats induced a remarkable increase of regucalcin mRNA in liver; the level was about 200% of control at 24 h after the administration of 2.0 mg/kg. The increase showed about 350% even at 6 h after the administration. Meanwhile, hepatic regucalcin mRNA level was not appreciably altered by a single subcutaneous administration of thyroxine (T4) (20, 40 and 80 mg/kg) or hydrocortisone (10 and 30 mg/kg) in rats. The present study demonstrates that the expression of hepatic regucalcin mRNA is stimulated by estrogen action in the liver nuclei of rats.
Mol Cell Biochem 1995 Feb 23
PMID:17 beta-Estradiol stimulates the expression of hepatic calcium-binding protein regucalcin mRNA in rats. 759 48

The expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats was investigated. The change of regucalcin mRNA levels was analyzed by Northern blotting using liver regucalcin complementary DNA (0.9 kb of open-reading frame). Regucalcin mRNA was expressed in the kidney cortex, and this expression was clearly increased by a single intraperitoneal administration of calcium chloride solution (5-15 mg Ca/100 g body weight) in rats; this increase was remarkable at 60-120 min after the administration. Thyroparathyroidectomy (TPTX) caused a slight decrease of regucalcin mRNA levels in the kidney cortex. However, the administration of calcium (10 mg/100 g) in TPTX rats produced a clear increase of regucalcin mRNA levels in the kidney cortex. The subcutaneous administration of calcitonin (10-100 MRC mU/100 g) or parathyroid hormone [1-34] (1-10 U/100 g) in TPTX rats which received calcium (10 mg/100 g) administration did not cause an appreciable alteration of regucalcin mRNA levels in the kidney cortex, suggesting that the mRNA expression is not stimulated by calcium-regulating hormones. The administration of trifluoperazine (TFP; 5 mg/100 g), an inhibitor of Ca2+/calmodulin action, completely blocked the expression of regucalcin mRNA stimulated by calcium administration. Now, calcium content in the kidney cortex was significantly elevated by a single intraperitneal administration of calcium (10 mg/100 g) in rats. The present study clearly demonstrates that the expression of regucalcin mRNA in the kidney cortex is stimulated by calcium administration in rats. This expression may be mediated through Ca2+/calmodulin action in the kidney cortex.
Mol Cell Biochem 1995 May 10
PMID:Expression of calcium-binding protein regucalcin mRNA in the kidney cortex of rats: the stimulation by calcium administration. 765 81

The effect of refeeding on the expression of Ca(2+)-binding protein regucalcin mRNA in the liver of fasted rats was investigated. When rats were fasted overnight, the hepatic regucalcin mRNA level was reduced about 70% of that in feeding rats. Refeeding produced a remarkable elevation of hepatic regucalcin mRNA level (about 150-170% of fasted rats). Liver regucalcin concentration was appreciably increased by refeeding, although it was not altered by fasting. The oral administration of glucose (2 g/kg body weight) to fasted rats caused a significant increase in hepatic regucalcin mRNA level. Moreover, hepatic regucalcin mRNA level was clearly elevated by a single subcutaneous administration of insulin (10 and 100 U/kg) to fasted rats. The hormonal effect was not further enhanced by the simultaneous administration of calcium chloride (250 mg Ca/kg) to fasted rats, although calcium administration stimulated regucalcin mRNA expression in the liver. The present study suggests that the expression of hepatic regucalcin mRNA stimulated by refeeding is significantly involved in the action of insulin and/or calcium as stimulating factors.
Mol Cell Biochem 1995 Jan 12
PMID:Expression of hepatic calcium-binding protein regucalcin mRNA is elevated by refeeding of fasted rats: involvement of glucose, insulin and calcium as stimulating factors. 775 40


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