Fig. 1
From: The genetics and screening of familial hypercholesterolaemia
The LDLR pathway. The LDL receptor (LDLR), part of a LDLR/clathrin/LDLRAP1(ARH) vesicle, binds to the ApoB in LDL particles, internalsing them (1) [26]. The receptor-ligand complex dissociate and LDLR is either recycled (2a and 3a) or degraded (2b and 3b). Residual cholesterol levels regulate the transcription of LDLR (4). PCSK9 is endogenously secreted from the Golgi apparatus where it binds to LDLR (5) [93]. Alternatively, PCSK9 can exogenously bind to LDLR (6). Once internalised to the hepatocyte, PCSK9 directs bound LDLR to the lysosome for degradation. Recent evidence suggests that PCSK9 can bind to LDL via ApoB in free circulation (7) [94]