Figure 4.

CP behaves like an integral membrane-associated protein. The supernatant S₁ fraction was centrifuged at 200,000g to give a P₂₀₀ microsomal membrane fraction, which was resuspended and divided into five equal fractions in buffer containing either 5 m NaCl, 5 m urea, 1 m Na₂CO₃, pH 10.9, or 1% (v/v) Triton X-100 and incubated on a shaker for 30 min at 4°C. The resulting suspension was recentrifuged for 60 min at 200,000g, providing pellet and soluble fractions. Shown here are the pellet fractions that were blotted and probed with CPA and CPB antibodies, as well as with actin, VIPP-1, and Sec12 antibodies as controls for peripheral and integral membrane-associated proteins, respectively. Similar experiments were performed four independent times.