Photoaffinity labelling of Ca<sup>2+</sup> channels with [<sup>3</sup>H]azidopine

Ferry, David; Rombusch, Martin; Göll, A.; Glossmann, Hartmut

doi:10.1016/0014-5793(84)80299-9

Cited by 90 publications

(27 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Otherwise incorporation into unrelated membrane structures (such as the nucleoside carrier) cannot be excluded. It should be pointed out that this requirement is only fulfilled by the experiments in [6]. Second, our results may help to understand the pharmacological effects (unrelated to Ca2 + -channel blockade) of racemic I ,4-dihydropyridines.…”

Section: Discussionmentioning

confidence: 80%

“…Thus the (-) enantiomers of the chirall,4-dihydropyridines nitrendipine [l] and Bay e 6927 or the (+) enantiomer of the benzoxadiazol 1,4-dihydropyridine PN 200-100 [18] are more potent in functional tests and with respect to receptor affinity compared to their optical antipodes. The optically pure enantiomers of chiral Ca' +-channel drugs are extremely valuable tools to discriminate channel receptors, e. g. in photoaffinity labelling experiments from binding sites unrelated to Ca2 + channels [6]. In addition to high-affinity receptor sites selective for 1,4-dihydropyridines, low-affinity sites have been described [l].…”

Section: Voltage-dependent Ca2mentioning

confidence: 99%

See 1 more Smart Citation

Human red‐blood‐cell Ca²⁺‐antagonist binding sites

Striessnig¹,

Zernig²,

Glossmann³

1985

European Journal of Biochemistry

Self Cite

View full text Add to dashboard Cite

The human red blood cell ghost Ca2+-antagonist binding sites were characterized with ( *)-[3H]nimodipine. The labelled 1,4-dihydropyridine bound in a non-cooperative, reversible manner with a K,, of 52 nM at 25°C to 9.65 pmol sites/mg ghost protein. The stereochemistry of the binding domain was evaluated with the optically pure enantiomers of chiral 1 ,Cdihydropyridines. In contrast to the 1,4-dihydropyridine-selective receptors on Ca2+ channels in electrically excitable tissues, the (+) enantiomer of nimodipine and the (-) enantiomer of the benzoxadiazol 1,4-dihydropyridine (PN 200 -11 0) were bound with higher affinity than the respective optical antipodes. The human red blood cell ghost [3H]nimodipine-labelled sites also interacted with the inorganic Ca2+-antagonist La3+ (increase in the number of binding sites), and were allosterically regulated by the optical enantiomers of the phenylalkylamine-type Ca2+-antagonists (e. g. verapamil, desmethoxyverapamil, methoxyverapamil). The benzothiazepines d-or I-cis-diltiazem were without effect. Nucleosides (adenosine x inosine > cytidine) were inhibitory at the nimodipine-labelled site, as were the nucleoside uptake inhibitors dipyridamole, hexobendine, dilazep, nitrobenzylthioinosine and nitrobenzylthioguanosine. The binding sites have essential sulfhydryl groups, show trypsin sensitivity, but are relatively heat stable. When nitrobenzylthioinosine was employed as a covalent probe to inactivate the red blood cell ghost nucleoside carrier,

show abstract

Section: Discussionmentioning

confidence: 80%

Section: Voltage-dependent Ca2mentioning

confidence: 99%

Human red‐blood‐cell Ca²⁺‐antagonist binding sites

Striessnig¹,

Zernig²,

Glossmann³

1985

European Journal of Biochemistry

Self Cite

View full text Add to dashboard Cite

show abstract

“…The dihydropyridine azidopine has been widely employed as a photoaffinity ligand, for both calcium channels and P-gp (Ferry et al 1984: Yang et al 1988. It is possible to evaluate the ability of resistance-modifying agents to interact directly with P-gp by examining their inhibition of [3H]azidopine cross-linking to the 170-kDa P-gp band on polyacrylamide gels.…”

Section: C) Cancer Research Campaign 1998mentioning

confidence: 99%

Reversal of P-glycoprotein-mediated multidrug resistance by XR9051, a novel diketopiperazine derivative

Dale¹,

Tuffley²,

Callaghan³

et al. 1998

Br J Cancer

View full text Add to dashboard Cite

Summary XR9051 (N-(4-(2-(6,7-Dimethoxy-1 .2,3,4,-tetrahydro-2-isoquinolyl)ethyl)phenyl)-3-((3Z,6Z)-6-benzylidene-1 -methyl-2.5-dioxo-3-piperazinylidene) methylbenzamide) was identified as a potent modulator of P-gtycoprotein-mediated multidrug resistance (MDR) following a synthetic chemistry programme based on a natural product lead compound. The Correspondence to: P Chartton has been well documented. but at present its role in solid tumours is less clear.A broad range of compounds has been identified that are able to rexverse the MDR phenotype by interacting with P-gp and blocking the efflux of cvtotoxics from cells. These compounds include peptides. steroids. calcium channel blockers. cardiox ascular drugys and immunosuppressix e and antifungal agents (reviewed by Ford. 1996). Their use has been limited bx the inabilitN to achiexe clinically effectixe plasma or tumour concentrations to inhibit P-gp function before non-specific. deleterious toxicities are encountered (Lum et al. 1993: Raderer and Scheithaeur. 1993). The requirement for more selectixe and potent agents as resistance modifiers has led to the identification of a number of secondgeneration modulators. such as a non-immunosuppressix e cxclosporin derivatixe SDZ PSC 833 (Boesch et al. 1991). an acridonecarboxamide derixatixe. GG918 (Hvafil et al. 1993). and a triazinoaminopiperidine derixitixe. S9788 (Pierre et al. 19921. These compounds are currentlx in clinical trial. The demonstration that potent modulators can oxercome resistance in P-gp-oxerexpressing cell lines and tumours is a vital step in answerinc the question of whether inhibition of P-gp function w ill be an effectix e therapeutic strategy.XR9051 (Figure 1) xas identified from a medicinal chemistrx programme based on a diketopiperazine originally isolated from the fermentation of a Streptomyces species. In this paper. we descnrbe the in X itro profile of XR905 1. wxhich illustrates its promise as a nexx drug for the treatment of MDR tumours. 885

show abstract

“…Identification of protein P-160 in this study by dihydropyridine-specific affinity chromatography is an independent confirmation of this conclusion. The peptide of similar molecular mass is labeled by photoaffinity dihydropyridine probes both in rabbit [16,38,401 and guinea-pig skeletal muscle membranes [41,421. Therefore, it is this polypeptide that includes a dihydropyridine-binding site and interacts with the affinity resin.…”

Section: Discussionmentioning

confidence: 99%

Purification and characterization of dihydropyridine receptor from rabbit skeletal muscle

Soldatov¹

1988

European Journal of Biochemistry

View full text Add to dashboard Cite

Digitonin and 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1 -propane sulfonate (Chapso) were used to solubilize the receptor of dihydropyridine calcium antagonists from the transverse tubule membranes of rabbit skeletal muscle. The receptor retained the ability for selective adsorption from either detergent extract by dihydropyridine-Sepharose. Incubation of the affinity resin with nitrendipine resulted in the elution of the receptor protein composed of two main polypeptides with molecular masses of 160 kDa and 53 kDa, as shown by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Only these two subunits were found in the receptor preparation purified to a specific dihydropyridine-binding activity of 2500 -2800 pmol/mg protein (60 -70% purity) from digitonin-solubilized membranes by a combination of wheat-germ-agglutinin -Sepharose, anion-exchange and dihydropyridine-Sepharose chromatography steps.The individual subunits were isolated in dodecyl-sulfate-denatured form from the preparation of the receptor, enriched by a two-step large-scale procedure applied to Chapso-solubilized membranes. The 160-kDa subunit slowly changed its apparent molecular mass to 125 kDa upon disulfide bond reduction without formation of novel peptides. This finding implies that 160-kDa subunit is cross-linked by intramolecular S-S bridge(s). Chemical deglycosylation with trifluoromethanesulfonic acid showed that the carbohydrate content of large and small subunits accounted for 7.5% and 6.6% by mass, respectively. The dihydropyridine receptor subunits are glycosylated through N-glycoside bonds only. In their ratio of polar to hydrophobic amino acid residues in the amino acid composition of the receptor subunits, these polypeptides behave rather as peripheral proteins. It is suggested that the main portion of polypeptide chains is located outside the membrane in contact with solvent.Dihydropyridine calcium antagonists, such as nifedipine, are known to be the most potent blockers of potential-dependent calcium channels [I], which play a key role in a number of secretory and regulatory processes in living cells. In a variety of muscle cells the voltage-operated calcium channels are involved in excitation/contraction coupling [2 -51 which underlies the use of specific calcium antagonists in the treatment of a number of cardiovascular disorders [6].The identification of the dihydropyridine receptors, generally considered as putative calcium channels, is now accessible since a number of radioactively labeled dihydropyridine derivatives have become available [7, 81. Rabbit white muscle transverse tubule membranes are certainly the richest source of the dihydropyridine receptor known [9]. These membranes have been reported to be suitable for the receptor purification when solubilized in digitonin [lo] or Chaps [ll]. The subunit composition of the purified receptor preparations, however, differed significantly. Receptor, purified as a slowly dissociating complex with [3H]nitrendipine, solubilized by digitonin, co...

show abstract

Photoaffinity labelling of Ca²⁺ channels with [³H]azidopine

Cited by 90 publications

References 19 publications

Human red‐blood‐cell Ca²⁺‐antagonist binding sites

Human red‐blood‐cell Ca²⁺‐antagonist binding sites

Reversal of P-glycoprotein-mediated multidrug resistance by XR9051, a novel diketopiperazine derivative

Purification and characterization of dihydropyridine receptor from rabbit skeletal muscle

Contact Info

Product

Resources

About

Photoaffinity labelling of Ca2+ channels with [3H]azidopine

Cited by 90 publications

References 19 publications

Human red‐blood‐cell Ca2+‐antagonist binding sites

Human red‐blood‐cell Ca2+‐antagonist binding sites

Reversal of P-glycoprotein-mediated multidrug resistance by XR9051, a novel diketopiperazine derivative

Purification and characterization of dihydropyridine receptor from rabbit skeletal muscle

Contact Info

Product

Resources

About

Photoaffinity labelling of Ca²⁺ channels with [³H]azidopine

Human red‐blood‐cell Ca²⁺‐antagonist binding sites

Human red‐blood‐cell Ca²⁺‐antagonist binding sites