|Detection of TGR5/GPBAR1 in HEK293 Human Cell Line by Flow Cytometry. HEK293 human embryonic kidney cell line transfected with human TGR5/GPBAR1 and eGFP was stained with either (A) Mouse Anti-Human TGR5/GPBAR1 APC‑conjugated Monoclonal Antibody (Catalog # FAB4286A) or (B) Mouse IgG2B Allophycocyanin Isotype Control (Catalog # IC0041A). View our protocol for Staining Membrane-associated Proteins.|
TGR5, also known as GPR131, GPBAR1, M-BAR, and BG37, is a 46-48 kDa member of the GPCR1 family of molecules. It is a 330 amino acid (aa) 7-transmembrane glycoprotein that is found on a wide variety of cell types. These include monocytes, macrophages, Kupffer cells, skeletal muscle and pancreatic acinar cells, autonomic enteric and sensory DRG neurons, liver sinusoidal endothelial cells, intestinal L and EC (enterochromaffin) cells, gallbladder epithelium and cholangiocytes (bile duct epithelium). Notably, TGR5 expression exhibits polarity with respect to plasma membrane location, and it may appear either on the cell surface or in intracellualr membrane compartments such as the ER, nucleus or multivesicular bodies. Initially considered to be coupled to G alpha s with cAMP production, it is now known to also interact with G alpha i, activating the ERK signaling pathway. Bile acids generated from cholesterol in hepatocytes are a known ligand for TGR5. Aside from their role in fatty acid absorption, BA ligation of macrophage/Kupffer cell TGR5 results in an anti-inflammatory environment. Over the aa that constitute the TGR5 extracellular domain, human and mouse share 73% aa sequence identity; over the entire ORF, human and mouse share 83% aa sequence identity.