LRPAP1 and Hypercholesterolemia: Fortunately, although the oxidative folding of LA4 resembles that of Ca++ binding defective LA5 mutants (such as S14A or E16K) leading to Familial Hypercholesterolemia, in vivo folding of LA4 within LDLR does not lead to misfolding, which might be related to the assistance of chaperones such as receptor-associated protein (RAP) [34, 40] or endoplasmic reticulum DNA J domain-containing protein 5 (ERdj5), [41].