(C) Effects of Htt-552 on lysosomal stability. The release of β-hexosaminidase from intact lysosomes incubated with Htt-552-18Q or Htt-552-100Q. PC12 cells were transfected with Htt-552 for 48 h. Cell lysates were used as Htt-552-riched lysates. The lysates containing Htt-552 were incubated with isolated lysosomes and the lysosomal β-hexosaminidase activity at time 0, 10, 20 and 30 min was determined. Release of all lysosomal β-hexosaminidase from the same batches of lysosomes was induced by incubation with 0.1% Triton X-100. Release of all lysosomal β-hexosaminidase from the same batches of lysosomes was induced by incubation with 0.1% Triton X-100. The values are means±SE of three independent experiments. 