Hsp40s play distinct roles during the initial stages of apolipoprotein B biogenesis

Abstract

Apolipoprotein B (ApoB) transports serum cholesterol. Intriguingly, ApoB levels are lipid-regulated via endoplasmic reticulum-associated degradation; yet whether this hydrophobic protein requires cytosolic Hsp40 chaperones during biogenesis is unknown. We show that two Hsp40s unexpectedly play opposing roles during ApoB folding versus degradation.