Isolation of mitochondria-associated ER membranes.

Organelles within cells are interconnected by physical associations or contact sites. In the last decade, many reports have shown that these interactions are functional domains that maintain cellular homeostasis. One of the best studied interactions is between endoplasmic reticulum (ER) and mitochondria via mitochondria-associated membranes or MAMs. MAMs are lipid rafts in the ER in close apposition to mitochondria, where multiple enzymatic activities converge to coordinately regulate cellular functions such as: the import of phosphatidylserine into mitochondria from the ER for decarboxylation to phosphatidylethanolamine, cholesterol esterification, calcium signaling, mitochondrial shape and motility, autophagy and apoptosis. In this chapter, we describe and discuss some of the methods to isolate and assay this interesting cellular region.