Apolipoprotein E (apoE)

Apolipoprotein (apo) E was initially described as a lipid transport protein and major ligand for low density lipoprotein (LDL) receptors with a role in cholesterol metabolism and cardiovascular disease

• apE has emerged as a major risk factor (causative gene) for Alzheimer's disease and other neurodegenerative disorders
  
  
• the three isoforms (apoE2, apoE3, and apoE4), which differ by only a single amino acid interchange, has elucidated their unique functions
  • the apoE variants relate to different amino acids at positions 112 and 158: cysteine in both for apoE2, arginine at both sites for apoE4, and respectively cysteine and arginine for apoE3 that is viewed as the wild type
    
    
• ApoE2 generally is most favourable and apoE4 least favourable for cardiovascular and neurological health (2)
  • however apoE2 homozygosity can precipitate type III hyperlipoproteinemia
    
    

Reference:

1. Mahley RW.Apolipoprotein E: from cardiovascular disease to neurodegenerative disorders.J Mol Med (Berl). 2016; 94: 739-746 .
2. Marais AD. Apolipoprotein E in lipoprotein metabolism, health and cardiovascular disease. Pathology. 2019 Feb;51(2):165-176. doi: 10.1016/j.pathol.2018.11.002