HMG-CoA reductase (Hmg2p)

yeast HMG-CoA reductase (Hmg2p) is the rate limiting enzyme in cholesterol synthesis
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 * example of physiological regulation of protein abundance via ERAD
 * when cholesterol levels are high, Hmg2p undergoes a lipid-induced structural change so that it resembles a misfolded protein --> targeted for destruction (Shearer et al., 2005; EMBO J). Thus when Hmg2p is not needed, it is constitutively degraded
 * direct recognition of Hmg2p by Hrd1p circumvents the need for many known Hrd1p adaptor proteins, including Der1p, Usa1p and Yos9p