Table 1.

The main differences among human apoE isoforms.

Isoform	AA residues		Domain interaction	Binding to LDLR	Lipoprotein-binding preference
	112	158
ApoE 2	Cysteine	Cysteine	No	Low affinity	HDL
ApoE 3	Cysteine	Arginine	No	High affinity	HDL
ApoE 4	Arginine	Arginine	Yes	High affinity	LDL

AA = amino acid.

LDLR = low density lipoprotein receptor.