HMGCR

HMG-CoA reductase is the rate-limiting enzyme for cholesterol synthesis and is regulated via a negative feedback mechanism mediated by sterols and non-sterol metabolites derived from mevalonate, the product of the reaction catalyzed by reductase. Normally in mammalian cells this enzyme is suppressed by cholesterol derived from the internalization and degradation of low density lipoprotein (LDL) via the LDL receptor. Competitive inhibitors of the reductase induce the expression of LDL receptors in the liver, which in turn increases the catabolism of plasma LDL and lowers the plasma concentration of cholesterol, an important determinant of atherosclerosis. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Aug 2008]

3-Hydroxy-3-Methylglutaryl-CoA Reductase

Catalyzes the conversion of (3S)-hydroxy-3-methylglutaryl-CoA (HMG-CoA) to mevalonic acid, the rate-limiting step in the synthesis of cholesterol and other isoprenoids, thus plays a critical role in cellular cholesterol homeostasis (PubMed:2991281, PubMed:21357570, PubMed:6995544).

HMGCR is the main target of statins, a class of cholesterol-lowering drugs (PubMed:11349148, PubMed:18540668).

Cholesterol biosynthetic process Source: CACAO
Coenzyme A metabolic process Source: InterPro
Isoprenoid biosynthetic process Source: GO_Central
Negative regulation of amyloid-beta clearance Source: ARUK-UCL
Negative regulation of MAP kinase activity Source: Ensembl
Negative regulation of protein catabolic process Source: ARUK-UCL
Negative regulation of protein secretion Source: ARUK-UCL
Sterol biosynthetic process Source: GO_Central
Visual learning Source: Ensembl

Peroxisome membrane; Endoplasmic reticulum membrane

Cytoplasmic: 1-9
Helical: 10-39
Lumenal: 40-56
Helical: 57-78
Cytoplasmic: 79-89
Helical: 90-114
Lumenal: 115-123
Helical: 124-149
Cytoplasmic: 150-159
Helical: 160-187
Lumenal: 188-191
Helical: 192-220
Cytoplasmic: 221-248
Helical: 249-275
Lumenal: 276-314
Helical: 315-339
Cytoplasmic: 340-888

N-glycosylated. Deglycosylated by NGLY1 on release from the endoplasmic reticulum (ER) in a sterol-mediated manner.
Undergoes sterol-mediated ubiquitination and ER-associated degradation (ERAD) (PubMed:12535518, PubMed:19458199, PubMed:21778231). Accumulation of sterols in the endoplasmic reticulum (ER) membrane, triggers binding of the reductase to the ER membrane protein INSIG1 or INSIG2 (PubMed:12535518, PubMed:19458199, PubMed:21778231, PubMed:22143767). The INSIG1 binding leads to the recruitment of the ubiquitin ligase, AMFR/gp78, RNF139 or RNF145, initiating ubiquitination of the reductase (PubMed:12535518, PubMed:19458199, PubMed:21778231). The ubiquitinated reductase is then extracted from the ER membrane and delivered to cytosolic 26S proteosomes by a mechanism probably mediated by the ATPase Valosin-containing protein VCP/p97 (PubMed:12535518, PubMed:19458199, PubMed:21778231). The INSIG2-binding leads to the recruitment of the ubiquitin ligase RNF139, initiating ubiquitination of the reductase (PubMed:22143767). Lys-248 is the main site of ubiquitination (PubMed:19458199). Ubiquitination is enhanced by the presence of a geranylgeranylated protein (PubMed:21778231).
Phosphorylated. Phosphorylation at Ser-872 reduces the catalytic activity.