Primary structure of an apical protein from Xenopus laevis that participates in amiloride-sensitive sodium channel activity
| Autor: | Olivier Staub, Bernard C. Rossier, François Verrey, D J Benos, T R Kleyman, Jean-Pierre Kraehenbuhl |
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| Rok vydání: | 1992 |
| Předmět: |
Epithelial sodium channel
Protein Conformation Sodium Molecular Sequence Data Xenopus chemistry.chemical_element Xenopus Proteins Kidney Epithelium Sodium Channels Amiloride Xenopus laevis SCN3A medicine Animals Tissue Distribution Amino Acid Sequence RNA Messenger Cloning Molecular Gene Library Sodium channel activity Base Sequence biology Sodium channel Cell Polarity Membrane Proteins Articles Cell Biology Apical membrane biology.organism_classification Molecular biology chemistry Bufo marinus medicine.drug |
| Zdroj: | The Journal of Cell Biology |
| ISSN: | 1540-8140 0021-9525 |
| DOI: | 10.1083/jcb.119.6.1497 |
| Popis: | High resistance epithelia express on their apical side an amiloride-sensitive sodium channel that controls sodium reabsorption. A cDNA was found to encode a 1,420-amino acid long polypeptide with no signal sequence, a putative transmembrane segment, and three predicted amphipathic alpha helices. A corresponding 5.2-kb mRNA was detected in Xenopus laevis kidney, intestine, and oocytes, with weak expression in stomach and eyes. An antibody directed against a fusion protein containing a COOH-terminus segment of the protein and an antiidiotypic antibody known to recognize the amiloride binding site of the epithelial sodium channel (Kleyman, T. R., J.-P. Kraehenbuhl, and S. A. Ernst. 1991. J. Biol. Chem. 266:3907-3915) immunoprecipitated a similar protein complex from [35S]methionine-labeled and from apically radioiodinated Xenopus laevis kidney-derived A6 cells. A single integral of 130-kD protein was recovered from samples reduced with DTT. The antibody also cross-reacted by ELISA with the putative amiloride-sensitive sodium channel isolated from A6 cells (Benos, D. J., G. Saccomani, and S. Sariban-Sohraby. 1987. J. Biol. Chem. 262:10613-10618). Although the protein is translated, cRNA injected into oocytes did not reconstitute amiloride-sensitive sodium transport, while antisense RNA or antisense oligodeoxynucleotides specific for two distinct sequences of the cloned cDNA inhibited amiloride-sensitive sodium current induced by injection of A6 cell mRNA. We propose that the cDNA encodes an apical plasma membrane protein that plays a role in the functional expression of the amiloride-sensitive epithelial sodium channel. It may represent a subunit of the Xenopus laevis sodium channel or a regulatory protein essential for sodium channel function. |
| Databáze: | OpenAIRE |
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