1.12.7.2 | crystals of the soluble form obtained using 20% polyethylene glycol 1500 as a precipitant, which belong to the monoclinic space group P21, with unit-cell parameters a = 60.57, b = 91.05, c = 66.85 A, beta = 101.46°, to 2.4 A resolution. No crystals appear for the membrane form |