Intracellular membranes help shape many of the mitochondria, ER, Golgi, secretory granules, lysosomes, and the nucleus.
Membranes localize enzymes, function as integral elements in excitation-response coupling, and provide sites of energy transduction, such as oxidative phosphorylation (mitochondria).
The internal membranes make possible the differentiation of activities within the cell, greatly increasing its working surface.
Membranes that define the organelles communicate with each other and the “outside.”
Mitochondrial membranes
The two lipoprotein layers in the mitochondrionMITOCHONDRION. The outer membrane encloses the entire mitochondrion and contains channels with TRANSPORT PROTEINS to move molecules and ions in and out of the organelle. The inner membrane folds into cristae and contains many ENZYMES important to cell METABOLISM and energy production (MITOCHONDRIAL ATP SYNTHASE).