PMU-Autor/inn/en
Paulmichl MarkusAbstract
Ion channels selectively permeable to chloride ions regulate cell functions as diverse as excitability and control of cell volume. Using expression cloning techniques, a complementary DNA from an epithelial cell line has been isolated, sequenced and its putative structure examined by site-directed mutagenesis. This cDNA, encoding a 235-amino-acid protein, gave rise to a chloride-selective outward current when expressed in Xenopus oocytes. The expressed, outwardly rectifying chloride current was calcium-insensitive and was blocked by nucleotides applied to the cell surface. Mutation of a putative nucleotide-binding site resulted in loss of nucleotide block but incurred dependence on extracellular calcium concentration. The unusual sequence of this putative channel protein suggests a new class of ion channels not related to other previously cloned chloride channels.
Useful keywords (using NLM MeSH Indexing)
Amino Acid Sequence
Animals
Base Sequence
Cell Line
Chloride Channels
Cloning, Molecular*
DNA/chemistry
DNA/genetics
DNA/isolation*
purification
Dogs
Electric Conductivity
Gene Expression*
Kidney
Kinetics
Membrane Proteins/chemistry
Membrane Proteins/genetics*
Membrane Proteins/physiology
Molecular Sequence Data
Mutagenesis, Site-Directed
Oocytes/metabolism
Plasmids
Transfection
Xenopus laevis