Three-dimensional structure of bladder membrane protein.

The naturally occurring crystals of the mammalian bladder membrane belong to the two-sided plane group p6 and have a lattice parameter of 160 A. The 3D reconstruction in negative stain at a resolution of 35 A in-plane and 45 A out-of-plane shows each motif to consist of twelve subunits elongated perpendicular to the crystal plane to a total height of about 50 A. Comparison with shadowed specimens shows that the protein particles revealed by negative stain are exclusively on one side of the membrane.