CRYSTALLIZATION AND PRELIMINARY-X-RAY ANALYSIS OF THE CYTOPLASMIC DOMAIN OF HUMAN ERYTHROCYTE BAND-3

A cytoplasmic domain of the human erythrocyte membrane protein band 3 (M(r) = 42,500), residues 1-379, expressed in and purified from E. col i, has been crystallized by the method of vapor diffusion in sitting d rops with subsequent streak-seeding at room temperature. Initial cryst als were grown from solutions containing 65-68% saturated ammonium sul fate at pH 4.9 and 2 mg/ml protein. Subsequent streak-seeding into sol utions of 50-53% ammonium sulfate at pH 4.9 and 7 mg/ml protein produc ed single crystals suitable for X-ray analysis, which contained pure p rotein as revealed by gel electrophoresis. The crystals belong to the monoclinic space group C2 with cell dimensions of a = 178.8 Angstrom, b = 90.5 Angstrom, c = 122.1 Angstrom and beta = 131.3 degrees and dif fract at least to 2.7 Angstrom resolution (at 100 K). A self-rotation function shows the presence of approximate 222 local symmetry. (C) 199 5 Wiley-Liss, Inc.