A comparison of the roles of the low density lipoprotein (LDL) receptor and the LDL receptor-related protein/alpha 2-macroglobulin receptor in chylomicron remnant removal in the mouse in vivo.

摘要: Two cell surface molecules, the low density lipoprotein (LDL) receptor and LDL receptor-related protein (LRP)/alpha 2-macroglobulin receptor, have been found to a role in removal of apoE-rich lipoproteins. To further study this process assess relative contributions these proteins chylomicron remnants, we used an anti-LDL antibody, activated alpha 39-kDa receptor-associated (RAP) as inhibitors remnant intact mice. The advantage is that were able use same litters animals batches for experiment. In cultured Chinese hamster ovary cells, antibody inhibited uptake degradation about 80% well did unlabeled remnants. It not affect or degradation. Activated inhibit normal cells but reported block lack receptors. Chylomicron remnants blocked effectively 2-macroglobulin. This confirmed two ligands are cross-competitors suggests primary mediator express receptor. vivo, pretreatment with decreased 5 min after injection by one-third. had small, reproducible effect on removal, decreasing it 7% at min. Injection affected slightly. A similar pattern, somewhat greater was seen hepatic ligands. Anti-LDL reduced half, 15%. Studies RAP provided results generally those 2-macroglobulin, although appears bind site recognized either addition sharing Together, add support hypothesis that, both receptors can play mouse vivo plays substantially role, making LRP difficult appreciate. true receptors.(ABSTRACT TRUNCATED AT 400 WORDS)