The human enzyme hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) limits the rate of cholesterol synthesis, a necessary process for cellular growth, in liver tissue. Phosphorylation of HMGCR inactivates the enzyme, which occurs via a negative feedback mechanism mediated by sterols and non-sterol metabolites derived from the product of the reductase reaction. Inhibitors of HMGCR (statins) exert anti-inflammatory effects and decrease the frequency of cardiovascular events by lowering plasma cholesterol. Additionally, intermediate products along the pathway catalyzed by HMGCR, which modulate signal transducing proteins such as Ras, provide possible ties between HMGCR regulation and new chemotherapeutic methods.
Background References
1. Hu HJ et al. Ethanol extract of Zhongtian hawthorn lowers serum cholesterol in mice by inhibiting transcription of 3-hydroxy-3-methylglutaryl-CoA reductase via nuclear factor-kappa B signal pathway. Exp Biol Med (Maywood) 241:667-74 (2016).
2. Rolyan H et al. Defects of Lipid Synthesis Are Linked to the Age-Dependent Demyelination Caused by Lamin B1 Overexpression. J Neurosci 35:12002-17 (2015).
Sequence Similarity
Belongs to the HMG-CoA reductase family.
Post-translational Modification
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). Accumulation of sterols in the endoplasmic reticulum (ER) membrane, triggers binding of the reductase to the ER membrane protein INSIG1. This INSIG1 binding leads to the recruitment of the ubiquitin ligase, AMFR/gp78 or RNF145, initiating ubiquitination of the reductase. 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. Lys-248 is the main site of ubiquitination. Ubiquitination is enhanced by the presence of a geranylgeranylated protein.
Western blot analysis of HMGCR on different lysates with Rabbit anti-HMGCR antibody (ET1702-41) at 1/5,000 dilution.
Lane 1: HeLa cell lysate Lane 2: THP-1 cell lysate Lane 3: HepG2 cell lysate Lane 4: Mouse testis tissue lysate Lane 5: Rat testis tissue lysate
Lysates/proteins at 20 µg/Lane.
Predicted band size: 98 kDa Observed band size: 100 kDa
Exposure time: 1 minute 40 seconds;
4-20% SDS-PAGE gel.
Proteins were transferred to a PVDF membrane and blocked with 5% NFDM/TBST for 1 hour at room temperature. The primary antibody (ET1702-41) at 1/5,000 dilution was used in 5% NFDM/TBST at 4℃ overnight. Goat Anti-Rabbit IgG - HRP Secondary Antibody (HA1001) at 1:50,000 dilution was used for 1 hour at room temperature.
HMGCR was immunoprecipitated in 0.2mg HeLa cell lysate with ET1702-41 at 2 µg/10 µl beads. Western blot was performed from the immunoprecipitate using ET1702-41 at 1/5,000 dilution. Anti-Rabbit IgG for IP Nano-secondary antibody (NBI01H) at 1/5,000 dilution was used for 1 hour at room temperature.
Lane 1: HeLa cell lysate (input) Lane 2: Rabbit IgG instead of ET1702-41 in HeLa cell lysate Lane 3: ET1702-41 IP in HeLa cell lysate
Immunohistochemical analysis of paraffin-embedded human small intestine tissue with Rabbit anti-HMGCR antibody (ET1702-41) at 1/100 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (ET1702-41) at 1/100 dilution for 1 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
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