[Human apolipoprotein B48 receptor].

Abstract

Unique candidate receptor membrane binding proteins, MBP 200 and 235, were identified in human monocyte-macrophages. The MBP binds and internizes chylomicrons, triglyceride (TG)-rich VLDL, and VLDL devoid of apo E, but not acetyl LDL, via a domain in apo B48. The MBP is named apo B48 receptor because the receptor-binding domain is within apo B48. The apo B48 receptor differs from the scavenger receptor family and LDL receptor family because it does not bind acetyl LDL and it binds VLDL devoid of apo E by an apo E-independent mechanism. Immunohisto-chemical studies indicate colocalization of anti-apo B48 receptor Ab and monocyte-macrophage specific Ab in human atherosclerotic lesion foam cells. This suggests that apo B48 receptor may contribute to foam cell formation and atherosclerosis in abnormal state with elevated TG-rich lipoproteins.