Topological analysis of Niemann-Pick C1 protein reveals that the membrane orientation of the putative sterol-sensing domain is identical to those of 3-hydroxy-3-methylglutaryl-CoA reductase and sterol regulatory element binding protein cleavage-activating protein.

摘要: The Niemann-Pick C1 (NPC1) protein is predicted to be a polytopic glycoprotein, and it contains region with extensive homology the sterol-sensing domains (SSD) of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-R) sterol regulatory element binding cleavage-activating (SCAP). To aid functional characterization NPC1, model NPC1 topology was evaluated by expression epitope-tagged proteins investigation epitope accessibility in selectively permeabilized cells. These results were further confirmed identification glycosylated that are located lumen endoplasmic reticulum. Our data indicate this glycoprotein 13 transmembrane domains, 3 large 4 small luminal loops, 6 cytoplasmic tail. Furthermore, our show putative SSD oriented same manner as those HMG-R SCAP, providing strong evidence domain functionally important.