Resolving the structure of the Ca2+ channel by photoaffinity labelling

Glossmann, Hartmut; Ferry, David; Striessnig, Jörg; Göll, A.; Moosburger, Kurt

doi:10.1016/0165-6147(87)90082-4

Cited by 62 publications

(28 citation statements)

References 18 publications

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“…Photoreactions with arylazido groups under UV irradiation and iodomycin with visible light share no common pathways, and correspondingly other reaction centers in the protein are selected, which may be part of the same binding site or another one (50,57). On the other hand, this differential photoreactivity has the advantage of localizing various epitopes of the three-dimensional binding pocket(s), albeit the number of sites remains elusive.…”

Section: Resultsmentioning

confidence: 99%

Localization of the Iodomycin Binding Site in Hamster P-glycoprotein

Demmer¹,

Thole²,

Kubesch³

et al. 1997

Journal of Biological Chemistry

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P-glycoprotein, the overexpression of which is a major cause for the failure of cancer chemotherapy in man, recognizes and transports a broad range of structurally unrelated amphiphilic compounds. This study reports on the localization of the binding site of P-glycoprotein for iodomycin, the Bolton-Hunter derivative of the anthracycline daunomycin. 125 I]iodomycin had been predominantly incorporated into the fragment 230 -312 of isoform I of hamster P-glycoprotein. According to models based on hydropathy plots, the amino acid sequence 230 -312 forms the distal part of transmembrane segment 4, the second cytoplasmic loop, and the proximal part of transmembrane segment 5 in the Nterminal half of P-glycoprotein. The binding site for iodomycin is recognized with high affinity by vinblastine and cyclosporin A. P-glycoprotein, which belongs to the large family of ABC 1 transporters (1), binds and transports a broad range of structurally unrelated compounds (2). Its overexpression may cause the phenomenon of multidrug resistance (MDR) during cancer chemotherapy, whereby the tumor cells become resistant to a variety of antineoplastic agents due to a reduced intracellular accumulation of drugs (2-4). The MDR phenotype can be overcome by modulators, i.e. substances that are bound by P-glycoprotein and inhibit its drug excluding function (3). The medically important substrates of P-glycoprotein comprise anticancer drugs such as Vinca alkaloids and anthracyclines (2-4) and approved drugs that turned out to be potent modulators such as verapamil (5, 6), calcium antagonists (7), and cyclosporins (8).The major issue of how P-glycoprotein can handle so many substrates has been mainly approached by photoaffinity labeling and mutagenesis studies. Mutants that arose spontaneously during drug selection of cells and thereby changed their resistance profile were detected in the first cytoplasmic loop of human MDR1 protein (Gly 185 3 Val) (9) and in transmembrane segment (TM) 6 of hamster P-glycoprotein (Gly 338 3 Ala/Ala 339 3 Pro) (10). Active mutagenesis identified further motifs and positions in the N-and C-terminal half of P-glycoprotein which influence substrate specificity (11, 12). For example, the exchange of amino acids in the first cytoplasmic loop (11), TM5, TM6, TM10, TM12 (13-16), and the cytosolic linker peptide (17) resulted in all in an altered multidrug resistance phenotype, suggesting that during binding and transport the substrate is recognized by multiple residues located either in the cytosolic, membraneous, or ectoplasmic domains.Hydropathy plots deduced from the primary sequence predict that P-glycoprotein consists principally of two symmetrical halves, each of which contain a membrane domain with six membrane-spanning segments and a subsequent cytosolic nucleotide binding fold (18 -20). The topology of P-glycoprotein in vivo, however, may be more variable than predicted, e.g. under certain experimental conditions, TM segments were detected outside the membrane and loops postulated to face the cytosol were foun...

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Section: Resultsmentioning

confidence: 99%

Localization of the Iodomycin Binding Site in Hamster P-glycoprotein

Demmer¹,

Thole²,

Kubesch³

et al. 1997

Journal of Biological Chemistry

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“…Obviously, occupancy of one component seems to be sufficient for channel inhibition and, as a consequence, stimulation of insulin release. Interestingly, for Ca2÷-channels in various tissues characterized with different (photo)-affinity probes, similar molecular masses of 140-170 kDa, 52-60 kDa and 32-35 kDa have been described for the protein components of these channels (Glossmann et al [28]5; Galizzi et al [29]; Glossmann et al [30]). Their relationship to the corresponding sulfonylurea-labeled polypeptides has to be elucidated.…”

Section: Discussionmentioning

confidence: 99%

Differential interaction of glimepiride and glibenclamide with the β-cell sulfonylurea receptor II. Photoaffinity labeling of a 65 kDa protein by [3H]glimepiride

Kramer¹,

Müller

Girbig

et al. 1994

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Glimepiride is a novel sulfonylurea for the treatment of type II-diabetic patients exhibiting different receptor binding kinetics to B-cell membranes with 8-9-fold higher kof f rate and 2.5-3-fold higher kon rate compared to glibenclamide (see accompanying paper (Miiller, G. et al. (1994) Biochim. Biophys. Acta 1191, 267-277)). To elucidate the molecular basis for this differential behaviour of glimepiride and glibenclamide, direct photoaffinity labeling studies using fl-cell tumor membranes were performed.

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“…However, partial detritylation also occurred. Therefore, the DMF was evaporated and the reaction mixture was taken up in 20 mL of a mixture of HOAc-MeOH (8:2) and heated for 1 h at 100 "C. After evaporation and chromatographic purification, two products were isolated: 70 mg (37%) of the 3'-N-formyl derivative 4 1-( 5-0 -Trityl-3-pyrazol-l-yl-3-deoxy-/3-~-arabinofuranosy1)thymine (Ira). To a solution of 175 mg (3 mmol) of pyrazole in 10 mL of DMSO was added 60 mg (1.5 mmol) of a 60% suspension of NaH.…”

Section: -[3-( 124-triazol-4-yl)-23-dideoxy-j3-~-eryt~ro -Pentofumentioning

confidence: 99%

Synthesis and antiviral activity of 3'-heterocyclic substituted 3'-deoxythymidines

Wigerinck¹,

Aerschot²,

Janssen³

et al. 1990

J. Med. Chem.

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Various 3'-deoxythymidine analogues with an heterocyclic five-membered ring in the 3'-erythro position have been synthesized. The pyrrol-1-yl (3) and the 1,2,4-triazol-4-yl (5) compounds were synthesized from 1-(3-amino-2,3-dideoxy-beta-D-erythro-pentofuranosyl)thymine. The pyrazol-1-yl (16a), imidazol-1-yl (16b), and 1,2,4-triazol-1-yl (16c) derivatives were obtained by epoxide opening of the corresponding 1-(2,3-anhydro-beta-D-lyxofuranosyl)thymines followed by 2'-deoxygenation. Only the 3'-pyrrol-1-yl derivative showed marginal antiviral activity against human immunodeficiency virus.

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Resolving the structure of the Ca2+ channel by photoaffinity labelling

Cited by 62 publications

References 18 publications

Localization of the Iodomycin Binding Site in Hamster P-glycoprotein

Localization of the Iodomycin Binding Site in Hamster P-glycoprotein

Differential interaction of glimepiride and glibenclamide with the β-cell sulfonylurea receptor II. Photoaffinity labeling of a 65 kDa protein by [3H]glimepiride

Synthesis and antiviral activity of 3'-heterocyclic substituted 3'-deoxythymidines

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