Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The existence of a high affinity receptor for 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in rat pancreas was biochemically demonstrated in this study. In order to study the properties of this putative receptor, we took advantage of the analysis of low ionic strength chromatin-localized 1,25(OH)2D3 receptor. Using this method, the susceptibility of receptor protein to enzymatic degradation was so decreased, and the contamination by plasma vitamin D binding protein (DBP) component was so efficiently eliminated that a specific, saturable binding for 1,25(OH)2D3 could be demonstrated in the saturation analysis and the peak for the receptor was consistently apparent in the sucrose density gradient analysis. The equilibrium dissociation constant (Scatchard Kd) was found to be 3.7 +/- 1.5 x 10(-10) (M), and the concentration of specific binding sites was calculated to be 1.22 +/- 0.40 (fmol/mg protein). The number of specific binding sites in the rat pancreas was only 0.44% of that present in rat intestine (277 +/- 19 (fmol/mg protein] and 6.7% of that in rat kidney (18.1 +/- 1.0 (fmol/mg]. However, when a correction is made for the 1,25(OH)2D3 receptor distribution in the tissues and expressed as the receptor concentration per receptor-containing cells, the rat pancreatic receptor level was calculated to be about 30% of the rat intestine. Sucrose density gradient sedimentation of this receptor yielded a value of 3.2 +/- 0.1 (S) for the sedimentation coefficient and this peak was displaceable by a 100-fold excess of nonradioactive 1,25(OH)2D3.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Cell Endocrinol 1988 Dec
PMID:Demonstration of a high affinity receptor for 1,25-dihydroxyvitamin D3 in rat pancreas. 285 Sep 52

A rapid procedure for fractionating salt-stable dynein subunits from high-salt extracts of Chlamydomonas axonemes has been developed using a high-pressure liquid chromatography system with an anion exchange column and gradient salt elution. Five distinct fractions are shown to be highly enriched for five distinct subunits or subunit complexes by SDS/polyacrylamide gel electrophoresis. ATPase activity and electron microscopy. Peaks 1 and 4 contain, respectively, the single-headed gamma-subunit and the two-headed alpha/beta-heteropolymer that form the outer arm in situ and are dissociated by salt exposure; both peaks are absent from the outer arm-less mutant pf-28. Peaks 2, 3 and 5 contain, respectively, two distinct single-headed species and a double-headed species that derive from inner arms; all three peaks are missing from the inner arm-less mutant pf-23. Sucrose-gradient sedimentation analysis confirms these assignments and provides additional information on the intermediate-chain and light-chain composition of the inner-arm species. Electron microscopy of the purified inner-arm species visualized by the quick-freeze deep-etch technique complements a previous analysis of outer-arm species. Each protein is shown to have a unique morphology, and both the inner- and outer-arm proteins clearly belong to a common family whose structural divergence presumably reflects functional specialization.
J Mol Biol 1987 Apr 05
PMID:High-pressure liquid chromatography fractionation of Chlamydomonas dynein extracts and characterization of inner-arm dynein subunits. 295 7

Specific receptors for 1,25-dihydroxyvitamin D3, the active hormonal form of vitamin D3, were demonstrated in low salt chromatin preparations from normal rat hearts. Sucrose gradient analysis of KCl-extracted chromatin yielded a significant (P less than 0.005) peak of specific [3H]1,25-dihydroxyvitamin D3 binding in the 3.6S region. The peak of [3H]1,25-dihydroxyvitamin D3 binding was abolished by excess 1,25-dihydroxyvitamin D3, but not by 50 nM 25-hydroxyvitamin D3 nor by 1.0 microM levels of estradiol-17B, cortisol, or promegestone, demonstrating steroid specificity characteristic for such receptors. Upon Scatchard analysis this putative cardiac 1,25-dihydroxyvitamin D3 receptor yielded a single binding component with high affinity (KD = 0.36 nM) and low capacity (Nmax = 33 fmol/g tissue). Coupled with evidence for the presence of calcium binding proteins in this tissue, these observations suggest functional roles for 1,25-dihydroxyvitamin D3 and its receptors in cardiac muscle, possibly in regulating intracellular effects of calcium.
J Mol Cell Cardiol 1986 Jan
PMID:1,25-Dihydroxyvitamin D3 receptors identified in the rat heart. 300 97

Two enzymes, alkaline phosphatase and acetylcholinesterase (AChE), have been shown previously to be components of the surface of the trematode parasite Schistosoma mansoni. In this study we report that both these enzymes and other serine hydrolases are susceptible to release from the S. mansoni tegumental membrane by a phosphatidylinositol-specific phospholipase C (PIPLC) of bacterial origin. These data suggest that AChE and alkaline phosphatase of S. mansoni, as in higher organisms, are anchored to the membrane via covalently attached phosphatidylinositol. The release of AChE from the vesicular fraction of the parasite with PIPLC occurs in a concentration-dependent manner. Sucrose gradient centrifugation of the PIPLC-released AChE showed a single 8.3 S molecular form, similar to that observed for AChE solubilized by Triton X-100. PIPLC removed large amounts of AChE from the surface of intact schistosomula in culture, with no impairment of the viability of the parasite. In this case, an increase in the overall levels of AChE in the intact parasite was observed after addition of PIPLC.
Mol Biochem Parasitol 1988 Jun
PMID:Acetylcholinesterase in Schistosoma mansoni is anchored to the membrane via covalently attached phosphatidylinositol. 313 66

A mouse monoclonal antibody (IgG1 isotype) against human C1q (MAb 130) is presented that activates C1 in serum through its antigen-binding sites at an optimal molar ratio of 3 MAbs:1 C1q. The antibody does not inhibit binding of C1q to IgG. Experiments with pepsin- and collagenase-digested C1q showed that MAb 130 binds to the fibril-like strands (arms) of C1q, close to the globular heads. Bivalency of MAb 130 was a requirement for C1-activation, but not for binding to C1q. Increasing the segmental flexibility of the intact antibody by reduction and alkylation destroyed its capacity to activate C1. A MAb against the globular heads of C1q completely inhibited C1-activation by aggregated IgG (AHG), but did not prevent activation by MAb 130. C1, reconstituted by adding C1q-stalks that lack the globular heads to C1q-depleted serum was not activated by AHG, whereas activation by MAb 130 was not affected. Activation of serum-C1 by AHG and MAb 130 was inhibited by addition of excess purified C1-inhibitor in a comparable and dose-dependent manner. Sucrose-gradient analysis indicated a predominance of stable complexes of a single C1q-molecule with three MAbs at the optimal activating ratio. When isolated and added to C1q-depleted serum, these complexes activated C1 efficiently. A mechanism for activation by MAb 130 is proposed that supports the "distortive" model of C1-activation.
Mol Immunol 1988 May
PMID:The distortive mechanism for the activation of complement component C1 supported by studies with a monoclonal antibody against the "arms" of C1q. 326 34

The binding of triiodothyronine (T3) to tadpole liver, intestine, and tail fin nuclei was consistent with a single class of binding sites. The KD for the binding of T3 to isolated nuclei from the liver (1.02 nM), intestine (1.40 nM), and tail fin (0.831 nM) nuclei were not significantly different. The number of binding sites for T3 in the nuclei isolated from each tissue were also not significantly different. Sucrose gradient centrifugation of the salt-extracted nuclear T3-receptor complex revealed that the S20,w was not significantly different for the complex from the liver (3.7 S), intestine (3.9 S), or tail fin (3.9 S). Similarly, the Stokes radii of the complex from the liver (3.65 nm), intestine (3.84 nm), and tail fin (3.99 nm) were not significantly different. Molecular weights of 57,000, 64,000, and 67,000 were calculated from the sedimentation coefficients and Stokes radii for the T3-receptor complex from the liver, intestine, and tail fin, respectively. The similarity of the physicochemical properties of the T3-receptor complex from each of the tissues studied is consistent with the hypothesis that the same receptor is capable of inducing tissue-specific biochemical changes.
Mol Cell Endocrinol 1987 Jul
PMID:Physicochemical properties of the triiodothyronine nuclear receptor from tadpole liver, intestine and tail fin. 349 30

The acetylcholine receptor protein from human muscle was extracted with the non-ionic detergent Triton X-100 and purified by affinity chromatography on alpha-Naja toxin sepharose 4B. Further purification on Dicap-MP sepharose 4B, a choline analog compound, led to ACHR preparations with specific activities of 2-7 nmol/mg protein. The isolated receptor, labeled with 125I-alpha-bungarotoxin was characterized by different methods and compared to ACHRs from Torpedo californica electroplax and rat-denervated skeletal muscle. Gel filtration on Ultrogel AcA 34 resulted in a stokes radius of 70 A for the receptor monomer and 99 A for the dimeric form. Sucrose density gradient centrifugation showed sedimentation coefficients of 9.1 S and 13.5 S. From these data the molecular weight of the ACHR monomer was estimated as 254 000 D and 540 000 D for the receptor dimer. The isoelectric point of the 125I-alpha-bgt-ACHR complex was determined by thin-layer isoelectric focussing to be pH 5. Purified ACHRs were used for immunization of rats and mice which developed an EAMG as verified by clinical observation and electrophysical measurements. Sera from the immunized animals as well as from myasthenia gravis patients were subsequently used to compare the cross-reactivity of ACHR preparations from different sources. While antibodies of rats immunized with Torpedo ACHRs cross-reacted with ACHR preparations from rat and human skeletal muscle, antibodies from mice immunized with rat ACHR only reacted with preparations from rats and mice. Antibodies from mice immunized with ACHR of human origin exhibited a broad cross-reactivity, as did antibodies from MG patients.
Mol Cell Biochem 1984 Sep
PMID:Physiochemical and immunological properties of acetylcholine receptors from human muscle. 649 23

X-ray diffraction patterns have been recorded from partially oriented specimens of gap junctions isolated from mouse liver and suspended in sucrose solutions of different concentration and thus of different electron density. Analysis of these diffraction patterns has shown that sucrose is excluded from the 6-fold rotation axis of the junction lattice for a length of about 100 A. This indicates that the aqueous channel of the junctions is in the closed, high resistance state in these preparations. Mapping of the sucrose-accessible space in the junction indicates that the cross-sectional area of the channel entrance on the cytoplasmic side of the membrane could be up to five times larger than the area of the transmembrane channel. Sucrose does not penetrate more than 20 A into the membrane along the channel. Apparently the aqueous channel, 8 to 10 A in radius for most of its length, is narrowed or blocked by a small feature about 50 A from the center of the gap. Very close interactions exist between the gap junction protein and the lipid polar head groups on the cytoplasmic surface of the membrane. In this region, the protein intercalates between the polar head groups. These results suggest that the gap junction protein may have a functional two-domain structure. One domain, with a molecular weight of about 15,000, spans one bilayer and half of the gap and is contained largely within a radius of 25 A from the 6-fold axis. The second domain is smaller and occupies the cytoplasmic surface of the gap junction membrane. Trypsin digestion removes about 4000 Mr from the cytoplasmic surface domain of the junction protein. Most of the material susceptible to trypsin digestion is located more than 28 A from the 6-fold axis.
J Mol Biol 1984 Apr 15
PMID:Gap junction structures. V. Structural chemistry inferred from X-ray diffraction measurements on sucrose accessibility and trypsin susceptibility. 671 84

Glutamic dehydrogenase extracted with tris buffer from fresh freeze-thawed rat heart mitochondria was purified by ammonium sulphate fractionation, affinity chromatography on GTP agarose, hydroxyapatite chromatography and concentration using a molecular sieve. The final specific activity is 80 units/mg protein. Thin gel SDS electrophoresis of the purified enzyme preparation after reduction with dithiothreitol shows a major band with a molecular weight of 38 000 Daltons. Two minor bands are also present. Sucrose density gradient centrifugation reveals a molecular weight of 230 000 Daltons for unreduced mitochondrial GDH activity. By gel filtration rat heart mitochondrial glutamic dehydrogenase has a major peak at 230 000 Daltons, a minor peak at 300 000 Daltons and some larger molecular weight species. Rat liver mitochondrial glutamic dehydrogenase has a minor peak at 230 000, a major peak at 300 000 and some larger molecular weight species. The rat liver mitochondrial glutamic dehydrogenase predominance at 300 000 is unchanged by incubation, extraction and purification with rat heart mitochondria. The purified GDH is stable frozen at -10 degrees C in tris-HCl buffer with EDTA. It loses activity at 4 degrees C especially when stored in 0.2 M phosphate buffer. It also loses activity when dialyzed for 24 h. This loss of activity is not completely prevented by adding nucleotides to the buffer (AMP or ADP) but is decreased by their presence.
J Mol Cell Cardiol 1984 Apr
PMID:Glutamic dehydrogenase from rat heart mitochondria. I. Purification and physical properties including molecular weight determination. 672 19

Antibodies to the RNase-sensitive RNP and to the RNase-resistant Sm nuclear antigens were used to affinity purify these antigens from a saline extract of rabbit thymus acetone powder. Determination of the protein subunits recovered by either glycine-HCl, pH 2.8, or 2.5 M MgCl2 elution on gradient sodium dodecyl sulfate-polyacrylamide electrophoresis containing mercaptoethanol revealed that RNP was composed of five proteins with mol. wts from 10,000 to 15,000 whereas Sm contained the same or similar five chains plus six additional subunits with mol. wts from 21,000 to 42,000. RNase treatment of the thymus extract increased the recovery in Sm of the same bands compared to untreated extract. Thus, RNP and Sm appear to have different numbers of protein components and RNP may be a subset of Sm. Sucrose gradient centrifugation of the 125I-labeled, pH 2.8 eluted antigens gave peaks of 3 and 6S for RNP and Sm, respectively. Sucrose gradient centrifugation of the crude untreated thymus extract followed by quantitative single radial immunodiffusion analysis of each fraction produced a broad peak from 16S to the top of the gradient while pretreatment of the extract with RNase resulted in a discrete 6S peak. These results indicate that in rabbit thymus acetone powder native RNP and Sm exist as larger polydisperse complexes with additional material including RNA and that after acid elution or RNase treatment the antigens are found in a smaller monodisperse form.
Mol Immunol 1982 Jun
PMID:Characterization of RNP and Sm ribonucleoprotein nuclear antigens. 681 Jan 1


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