Intracellular proteins are targeted for proteolytic degradation in the lysosome with the aid of chaperones. Heat shock cognate 71 kDa protein (HSPA8) acts as the constitutive chaperone that binds KFERQ-domain containing substrates in the cytosol. Consequently, the Hspa8:Substrate complex translocates from cytosol to lysosomal membrane where it binds to Lysosome-associated membrane glycoprotein 2 (LAMP2a). Subsequently, HSPA8 is released and Heat shock protein HSP 90 binds to the lysosomal luminal end of LAMP2a. Binding of HSP90 stabilizes LAMP2 to multimerize into a 700 kDa complex (Bandyopadhyay U et al. 2008). This facilitates the internalization of substrate into the lumen. Experiments confirming this binding were performed on rat models.
Bandyopadhyay, U, Sridhar, S, Kaushik, S, Kiffin, R, Cuervo, AM
Bandyopadhyay, U, Kaushik, S, Varticovski, L, Cuervo, AM
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