Figure 7.

Degradation of full-length and exon-1 Htt by CMA. A, Kinetics of degradation of Htt in fibroblasts maintained in the presence or absence of serum. Half-lives are indicated. B, Immunoblot for Htt in the indicated subcellular fractions isolated from human fibroblasts in culture, rat liver and kidney, and mouse liver. Hom, homogenate; Cyt, cytosol; ER, endoplasmic reticulum; Mit, mitochondria; Lys, lysosomes. C, Immunoblot for Htt and LAMP-1 (L-1) of homogenates and lysosomes from fibroblasts maintained in the presence or absence of serum. D, Immunoblot for the indicated proteins of lysosomal membranes (Memb.) and matrices isolated from mouse liver. Where indicated, mice were injected with leupeptin 2 h before lysosomal isolation. Cath A, Cathepsin A. E, Immunoblot for the indicated proteins of mouse lysosomes subjected to washes with MOPS, 1 m NaCl, 0.1 m NaCO₂, or 1% Triton X-100. L-2, LAMP-2. F, Immunoblot for Htt and GAPDH of lysosomes incubated for the indicated times in isotonic media. G, Immunoblot for Htt of the indicated fractions isolated from liver and kidney of ¹⁸QHtt and ¹¹¹QHtt knock-in mice. H, Immunoblots for the indicated proteins in cells expressing full-length or exon1 ²³QHtt and ¹⁴⁵QHtt control (Ctr) or transfected with a vector expressing human LAMP-2A (hL-2A).