Figure 5

Cα1 and Cβ2 proteins are stabilized by RIα. 293T cells were untransfected (M) or transfected with fixed amounts of either pDeCα1 (300 ng) or pDeCβ2 (1400 ng) in conjunction with 1280 ng (bars 4 to 7) or without (bars 1-3) pDeRIα for 24 h. Cell extracts were adjusted to 1 mg total protein/mL and assayed for PKA-specific phosphotransferase activity in the absence (- cAMP) and presence (+ cAMP) of 320 nM cAMP. Data points represent pmol ATP transferred/min/mg protein) +/- SD (n = 3). The relative activities of Cβ2 and Cα1 in the absence of RIα were significantly different (* p < 0.02, bars 2 and 3). When Cα1 and Cβ2 were co-transfected with RIα the relative activities were indistinguishable (bars 5 and 7, ns).