Table 1.

Main differences between ApoE2 and ApoE4 [10–13].

	ApoE2	ApoE4
Isoform difference	Cys-112 Cys-158	Arg-112 Arg-158
Structure difference	Cys-158 disrupts the salt bridge	Domain interaction (formation of a salt bridge between Arg-61and Glu-255)
Protein stability	High	Very low
Binding preferences	Preferentially binds to small phospholipid-rich HDL Severely defective in LDL receptor binding activity (<2% binding activity compared with ApoE3)	Binds preferentially to large, triglyceride-rich VLDL Binds avidly to LDL receptors
Serum lipid association	Tends to be associated with increased levels of ApoE and triglyceride and decreased levels of ApoB and cholesterol	Tends to be associated with decreased ApoE but increased ApoB and cholesterol levels

Arg: arginine; Cys: cysteine; HDL: high-density lipoprotein; LDL: low-density lipoprotein; VLDL: very-low-density lipoprotein.