Fig. 5.

β₃ subunit is dominantly expressed and is the major form of β subunit of the N-type Ca²⁺channels in PC12 cells. A, Four β subunit-specific antibodies recognize native β subunits from rat tissues. Shown are ECL immunoblots of crude rat tissue membranes stained by four affinity-purified β subunit-specific antibodies. Crude rat brain membranes were probed with polyclonal antibodies to β₁, β₃, and β₄ subunits, and rat cardiac microsome membranes were probed with polyclonal antibodies to β₂ subunit. B, Expression of β₃ and β₂ subunit protein in PC12 cells. Shown are an ECL immunoblot of crude PC12 membranes stained with affinity-purified β₃ subunit antibody and an ECL immunoblot of the eluate from a β₂ antibody affinity column stained with β₂ antibody. C, Association of different β subunits with the α_1Bsubunit of the PC12 N-type Ca²⁺ channel. Shown is the immunoprecipitation of [¹²⁵I]ω-CgTX GVIA receptors by protein G (PG), four β subunit antibodies, and polyclonal antibodies against α_1B subunit from undifferentiated and differentiated PC12 cells. The error bar represents the SE of three replicates.