ATP-regulated chloride conductance in endoplasmic reticulum (ER)-enriched pig pancreas microsomes
| Autor: | Aleksander Edelman, Béatrice Bégault, Takis Anagnostopoulos |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
GTP'
Swine Biophysics Endoplasmic Reticulum Biochemistry Adenosine Triphosphate Chlorides Chloride Channels Microsomes Stilbenes medicine Animals Nucleotide Pancreas chemistry.chemical_classification Liposome Binding Sites Kinase Endoplasmic reticulum Electric Conductivity Conductance Cell Biology Adenosine Glycolates chemistry Liposomes Microsome medicine.drug |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 1152:319-327 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/0005-2736(93)90264-z |
| Popis: | The Cl- conductance of endoplasmic reticulum-enriched pancreatic microsomes was identified. Its regulation by nucleotides was investigated by measuring the rate of cation ionophore-induced microsome swelling in the presence of an inward Cl- gradient. The conductance was solubilized and reconstituted into liposomes. The Cl- conductance in intact microsomes was inhibited by stilbene (10(-4) M) and indanyloxyacetic acid (10(-5) M) derivatives. ATP increased Cl- conductance with half-maximal stimulation at 8 x 10(-6) M. Other trinucleotides (GTP, CTP and UTP) were without effect at 10(-4) M. The non-hydrolysable analogue of ATP, adenosine 5'-[beta gamma-methylene]triphosphate (AppCH2p) increased Cl- conductance with a potency similar to that of ATP. The same concentration of adenosine 5'-[gamma-thio]triphosphate (ATP gamma S) which is a substrate for kinases, had no effect. ATP stimulation of Cl- conductance was inhibited by stilbene derivatives. The data suggest the presence of at least one ATP-binding site, and show that the ATP does not need to be hydrolyzed and that its spatial conformation is important for activating the Cl- conductance. Solubilized microsomal proteins reconstituted into liposomes retained their stilbene-inhibited, ATP-stimulated Cl- conductance. A 167 kDa protein was detected by anti-CFTR antibodies in the intact microsomes, but not in the solubilized proteins. The 64 kDa protein (a component of a ubiquitous Cl- channel) was detected in the both intact and solubilized microsomes. These results suggest that this Cl- conductance is not a CFTR protein. |
| Databáze: | OpenAIRE |
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