Intracellular proteins are targeted for proteolytic degradation in lysosome with the aid of chaperones. Heat shock cognate 71 kDa protein (HSPA8) transports substrates from the cytosol to the lysosomal membrane where it binds to Lysosome-associated membrane glycoprotein 2 (LAMP2a). Subsequently, LAMP2a forms a multimeric complex stabilized with the aid of HSP90 and glial fibrillary acidic protein (GFAP). This multimer allows the transfer of substrate into the lumen. The stability of this complex is regulated by the dynamics of GFAP and elongation factor 1α (EEF1A1). During autophagy, a phosphorylated version of GFAP remains bound to EEF1A1. When GTP becomes available, EEF1A1 dissociates from GFAP and binds with GTP in the cytosol. Subsequently, EEF1A1 is translocated from lysosomal membrane to cytosol (Bandyopadhyay U et al. 2010). Experiments confirming this binding were performed in rats.
Cuervo, AM, Kiffin, R, Sridhar, S, Kaushik, S, Bandyopadhyay, U
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