title: Co-expression of sulfonylurea receptors and KATP channels in hamster insulinoma tumor (HIT) cells. Evidence for direct association of the receptor with the channel.
abstract: Cell membranes isolated from hamster insulinoma (HIT T15) cells at passages 65-74 contain high and low affinity receptors for a sulfonylurea derivative, 5-[125I]iodo,2-hydroxyglyburide (KD values of approximately 7 nM and 16 microM). Between passages 75 and 85, the estimated B(max) for the high affinity receptor decreases approximately 10-fold from approximately 1.6 to 0.16 pmol/mg membrane protein. By contrast, the density of low affinity binding sites, 800-1000 pmol/mg, is unaltered. The drop in high affinity receptors is paralleled by a decrease in the density of KATP channels assessed using patch-clamp and 86Rb(+)-efflux techniques. These results strongly support the idea that the high affinity sulfonylurea receptor is an integral part of the KATP channel.
authors.affiliation: Department of Medicine, Baylor College of Medicine, Houston, Texas 77030.
authors.forename: L
authors.initials: L
authors.lastname: Aguilar-Bryan
authors.forename: C G
authors.initials: CG
authors.lastname: Nichols
authors.forename: A S
authors.initials: AS
authors.lastname: Rajan
authors.forename: C
authors.initials: C
authors.lastname: Parker
authors.forename: J
authors.initials: J
authors.lastname: Bryan
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000345:Affinity Labels; D000818:Animals; D001345:Autoradiography; D001692:Biological Transport; D006224:Cricetinae; D004591:Electrophoresis, Polyacrylamide Gel; D005905:Glyburide / Q000031:analogs & derivatives / Q000378:metabolism; D007340:Insulinoma / Q000378:metabolism*; D007457:Iodine Radioisotopes; D015221:Potassium Channels / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism; D064233:Sulfonylurea Receptors; D014407:Tumor Cells, Cultured
chemical_list: D018528:ATP-Binding Cassette Transporters; D000345:Affinity Labels; D007457:Iodine Radioisotopes; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; C064021:5-iodo-2-hydroxyglyburide; D000255:Adenosine Triphosphate; D012413:Rubidium; D005905:Glyburide