Domain structure of 3-hydroxy-3-methylglutaryl coenzyme A reductase, a glycoprotein of the endoplasmic reticulum.

摘要: We present and evaluate a model for the secondary structure membrane orientation of 3-hydroxy-3-methylglutaryl coenzyme A reductase, glycoprotein endoplasmic reticulum that controls rate cholesterol biosynthesis. This is derived from proteolysis experiments separate 97-kilodalton enzyme into two domains, an NH2-terminal membrane-bound domain 339 residues COOH-terminal water-soluble 548 projects cytoplasm contains catalytic site. These domains were identified by reaction with antibodies against synthetic peptides corresponding to specific regions in molecule. Computer modeling reductase structure, based on amino acid sequence as determined molecular cloning, predicts 7 membrane-spanning regions. Analysis gene reveals each proposed region encoded exon separated adjacent intron. The predicted contain beta-structures flanked series amphipathic helices, which together may constitute active bears some resemblance rhodopsin, photoreceptor protein retinal rod disks only other intracellular whose known.