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. 2005 Dec 14;25(50):11693–11709. doi: 10.1523/JNEUROSCI.2766-05.2005

Figure 2.

Figure 2.

Comparison of activity levels of BACE1, BACE2, and α-secretase in cultured neurons and astrocytes. A, Protein extracts (20μg each) from cultured cortical neurons and astrocytes were immunoblotted using antiserum against BACE1, BACE2, PS1, neuron-specific β3-tublin, and glia-specific GFAP. Note that BACE1 was more abundant in neurons compared with glial cells, whereas BACE2 was more abundant in glial cells; PS1 levels in neurons were similar to that of glial cells. B–E, Mass spectrometric analysis of secreted human Aβ peptides from conditioned media of cultured neurons (B) and glial cells (C–E) infected with adenovirus expressing APPswe using PS1 Ciphergen ProteinChip system coated with 6E10, a monoclonal antibody specific to N termini of human Aβ peptides. The asterisks denote peaks corresponding to human Aβ peptides; the mass of each peptide is in parentheses. M/Z, Mass-to-charge ratio. F, The signal intensities of Aβ1–15, Aβ1–16, Aβ1–19, and Aβ1–20 were normalized to that of Aβ1–40, and the ratio is plotted as a function of type of cells. Note that cultured astrocytes showed higher levels of BACE2 and α-secretase activities than that of cultured neurons (n = 4; p < 0.001, Student's t test).