FIGURE 9.

Existence of PRiMA-linked G₄ AChE-BChE hybrid tetramers in chicken brain. A, sedimentation profiles of AChE and BChE molecular forms in extracts from adult chicken brain, as analyzed in Fig. 1A. B, G₂ fractions and G₄ fractions shaded in A were immunoprecipitated with anti-chicken AChE antibody (3D10) or anti-chicken BChE antibody (7D11) and absorbed onto protein G beads. AChE and BChE activities were determined by Ellman assays. C, immunodepletion of AChE-BChE hybrid molecules with 3D10 antibody. Samples of chicken brain extracts were incubated with or without 3D10 antibody and absorbed onto protein G-agarose beads, and the supernatant was analyzed by sedimentation in sucrose density gradients, as in Fig. 1A. The observed decrease of BChE activity after immunoprecipitation by 3D10 antibody showed that in BChE tetramers, ∼15% of BChE subunits were included in AChE-BChE hybrid tetramers (lower panel). The enzymatic activities are expressed in arbitrary units. The values are the means ± S.E., each with triplicate samples (n = 3). Representative gradient profiles are shown (n = 3). IP, immunoprecipitation.