We next explained how to calculate the deformation of the membrane as a result of the spontaneous curvature c 0 induced by a local asymmetric Ca + concentration between the inside and outside of the membrane. Assuming that only a small patch of the membrane of area a 0 near the north pole changed its spontaneous curvature to a value of C 0 , while the other part of the membrane has a zero spontaneous curvature, c 0 is modeled as a function of the surface area a calculated from the north pole