Figure 3.

APPβ is produced intracellularly in NT2N neurons. Culture dishes containing >99% pure NT2N cells were metabolically labeled with [³⁵S]methionine for 16 h. Cells were rinsed twice with PBS and then incubated on ice for 20 min with PBS alone (lane 1), with 10 μg/ml trypsin (lane 2), or with 10 μg/ml trypsin and 0.1% Triton X-100 (lane 3). The cells were processed for immunoprecipitation with the anti-APPβ antibody 53, as described in Materials and Methods.