Solubilization of membrane-bound adenylate cyclase of isolated rat adrenal cortex cells

The membrane-bound adenylate cyclase (ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1) of isolated rat adrenal cortex cells can be rendered soluble using 0.02 M Lubrol 12A9. The solubilized enzyme can be filtered through Millipore filters with pores 0.22 μm in diameter. Using gel filtration, on Sephadex G-200, adenylate cyclase activity was eluted with a distribution coefficient of 0.139, whereas on Sephadex G-100 the activity was eluted in the excluded volume. Half-maximum activation of the postulated guanyl nucleotide regulator site of adenylate was achieved with 5′-guanylyl-imidodiphosphate at a concentration of 1 · 10^?6 M. In contrast, however, using intact isolated rat adrenal cortex cells the guanyl nucleotide regulator site could not be stimulated by 5′-guanylyl-imidodiphosphate.