Membrane estrogen receptors signal to determine transcription factor function.

Estrogen receptors (ER) alpha and beta as well as many other steroid receptors are found both within the nucleus and outside the nucleus. This includes extra-nuclear receptors in many organelles, including mitochondria, endoplasmic reticulum, cytosolic endosomes, and membrane lipid rafts, such as caveolae. The functions of these receptors in the various extra-nuclear cell organelles are not well described, but progress for understanding steroid receptor signaling from the membrane has advanced. In this Review I will discuss the enlarging role of membrane ER signaling to the expression, cell localization, and function of transcription factors that are essential to mediate cell physiology or pathophysiology in many organs.