The estrogen receptor activity cycle: dependence on multiple protein-protein interactions.

The estrogen steroid hormone receptor (ER) is a member of a family of related hormone-inducible transcriptional regulators. The function of these receptors is dependent on multiple protein-protein interactions with other cellular polypeptides. These contacts regulate the four steps in the receptor "life cycle": synthesis and nuclear transport, priming/storage, activation, and recycling. Each of these steps is mediated by the formation of distinct protein complexes and results in a temporal and spatial regulation of ER activity. This review focuses on the cellular proteins that interact with the ER, and the role that these interactions are believed to play in the regulation of ER.