 For example, the neuron-specific calexcitin has been found to have an excitatory effect on neurons, and interacts with proteins that control the firing state of neurons, such as the voltage-dependent potassium channel.Compartmentalization of calcium binding proteins such as calretinin and calbindin-28 kDa has been noted within cells, suggesting that these proteins perform distinct functions in localized calcium signaling.It also indicates that in addition to freely diffusing through the cytoplasm to attain a homogeneous distribution, calcium binding proteins can bind to cellular structures through interactions that are likely important for their functions.