The Calcium-Dependent Interaction of S100B with Its Protein Targets

Abstract

S100B is a calcium signaling protein that is a member of the S100 protein family. An important feature of S100B and most other S100 proteins (S100s) is that they often bind Ca2+ions relatively weakly in the absence of a protein target; upon binding their target proteins, Ca2+-binding then increases by as much as from 200- to 400-fold. This manuscript reviews the structural basis and physiological significance of increased Ca2+-binding affinity in the presence of protein targets. New information regarding redundancy among family members and the structural domains that mediate the interaction of S100B, and other S100s, with their targets is also presented. It is the diversity among individual S100s, the protein targets that they interact with, and the Ca2+dependency of these protein-protein interactions that allow S100s to transduce changes in[Ca2+]intracellularlevels into spatially and temporally unique biological responses.