in a search for an appropriate ionic messenger it is noted that inorganic cations have a wider range of interactions with biomolecules than anions , that the prevalent monovalent cations have too high a flux across lipid membranes and too weak an interaction with molecules in aqueous domains , that trivalent cations can not as effectively be transported across lipid membranes , that divalent cation movement across lipid membranes can be well modulated and their divalent charge allows for a wide range of binding constants with biological molecules , and that for reasons of radius-compatibility with polypeptide chelation and due to the lack of stringent crystal field requirements , ca2+ is a most suitable divalent cation for a messenger role .
C0007447
cations
C0007448
divalent cation