apolipoprotein B-48 receptor; apoB48 receptor; apoB-48R (APOB48R, APOBR)
Jump to navigation
Jump to search
Function
- macrophage receptor
- binds to the apolipoprotein B48 (APOB) of dietary triglyceride (TG)-rich lipoproteins (TRL) or to a like domain of APOB in hypertriglyceridemic very low density lipoprotein (HTG-VLDL)
- binds & internalizes TRL when out of the context of the macrophage
- may provide essential lipids to reticuloendothelial cells
- could also be involved in foam cell formation with elevated TRL & remnant lipoprotein (RLP)
- mediates the rapid high-affinity uptake of chylomicrons (CM), HTG- VLDL, & trypsinized (tryp) VLDL devoid of APOE in vitro in macrophages
- 2 forms in macrophages
- the membrane-binding proteins 200 kD (MBP 200)
- 235 kD (MBP 235), that can be reduced into a single active ligand-binding species with intermediate mobility (MBP 200R)
Structure
homodimer
Compartment
- cell surface
- binds monocyte-macrophage membrane
- thought to be anchored in the membrane through an interaction with an integral membrane protein
Alternative splicing
named isoforms=3
Expression
- expressed in peripheral blood leukocytes > bone marrow = spleen > lymph node, & only faintly visible in appendix & thymus
- expressed in the brain, heart, kidney, liver, lung, pancreas, & placenta
- expressed primarily by reticuloendothelial cells: monocytes, macrophages, & endothelial cells
- suppressed significantly by PPARA & PPARG in THP-1 & blood-borne monocyte-macrophages
- decreased after pitavastatin treatment in peripheral blood macrophages & remnant lipoprotein (RLP)-induced foam cell formation
Pathology
- expressed in atherosclerotic lesion foam cells
- genetic variations in APOB48R may be a cause of susceptibility to hypercholesterolemia
Notes
- also see LDL receptor