FIGURE 3.
The association of GABABR1 and GABABR2 is low in a brain microsomal fraction. A, coimmunoprecipitation of GABABR1 and GABABR2 from different membrane preparations. P2 (lanes 1 and 2) and P3 fractions (lanes 3 and 4) were prepared from adult rat brains. Samples were immunoprecipitated with control IgG (lanes 1 and 3) or GABABR2 antibodies (lanes 2 and 4), separated by SDS-PAGE and immunoblotted with GABABR1 antibodies. B, the P2 and P3 fractions prior to immunoprecipitations were used to control the abundance of GABABR1, GABABR2, and calnexin. C, immunoblots for immunoprecipitations of GABABR1 from P2 or P3 were analyzed by densitometry and average values ± S.E. were plotted for each fraction (n = 3 independent fractionation and immunoprecipitation experiments). D, same as above for the total abundance GABABR1 in each fraction. E, values of immunoprecipitations were normalized to the abundance of GABABR1 in the corresponding fraction and average values ± S.E. were plotted for each fraction (***, p < 0.001).