The distribution of elements in cells

The selective uptake of elements by proteins can be based on several routes: (a) the equilibrium binding of different elements by different protein ligands using charge, size, electron affinity and stereochemical preferences; (2) kinetic insertion of an element into such a coordination site of a protein; (3) removal of the element to a special compartment by pumping followed by (1) or (2). A cellular system also limits the amount of each type of metal-binding apoprotein by genetic regulation of its symbiosis with element uptake. Such a limitation generates much greater selectivity. Finally we consider how the observed selection of elements by proteins has changed in evolution through changes of availability of elements and their combinations in the environment(1). (C) 2000 Elsevier Science S.A. All rights reserved.