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 (K(D) values of ~7 nM and 16 μM). Between passages 75 and 85, the estimated B(max) for the high affinity receptor decreases ~10-fold from ~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 K(ATP) 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 K(ATP) channel.
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|State||Published - 1992|