Cook N J, Molday L L, Reid D, Kaupp U B, Molday R S
Max-Planck Institut für Biophysik, Abteilung Molekulare Membranbiologie, Frankfurt am Main 71, Federal Republic of Germany.
J Biol Chem. 1989 Apr 25;264(12):6996-9.
Although there have been several reports pertaining to the existence of the cGMP-gated channel in the disk membrane of rod photoreceptors, its density there relative to that of the photoreceptor plasma membrane is unknown. Using immunoblotting, immunohistochemical, and reconstitution techniques on purified disk and plasma membrane preparations, we found that the density of channels in the plasma membrane was at least 50-fold higher than that of the disk membrane. Purification of membrane fractions without prior digestion of cytoskeletal components by mild trypsinization was found to increase the amount of channel protein present in disk membrane preparations. We propose that the presence of the channel protein in rod disk membrane preparations is an artifact arising from fusion of plasma membrane components during permeabilization of the photoreceptor cell.
尽管已有多篇报道提及视杆光感受器盘膜中存在环磷酸鸟苷门控通道，但其在盘膜中的密度相对于光感受器质膜的密度仍不清楚。我们运用免疫印迹、免疫组织化学以及在纯化的盘膜和质膜制剂上进行重组技术，发现质膜中通道的密度比盘膜中的密度至少高50倍。我们还发现，在不先用温和胰蛋白酶消化细胞骨架成分的情况下纯化膜组分，会增加盘膜制剂中通道蛋白的含量。我们认为，视杆盘膜制剂中通道蛋白的存在是光感受器细胞通透化过程中质膜成分融合产生的假象。
