The function of mitochondria, endoplasmic reticulum (ER), and mitochondria-associated ER membranes (MAMs (IMAGE)
Caption
(A) Mitochondria consist of the outer mitochondrial membrane (OMM), inner mitochondrial membrane (IMM), intermembrane space (IMS), and matrix. The OMM contains a number of proteins, such as voltage-dependent anion channel (VDAC), which keeps Ca2+ homeostasis in mitochondria, and regulators of mitochondrial fusion, such as mitochondrial fusion protein 2 (MFN2). Mitochondrial fission is mediated by the recruitment of dynamin-related protein 1 (DRP1) on the OMM. Mitochondrial Ca2+ uniporter (MCU) is a major conduit in the IMM, mediating Ca2+ uptake into the mitochondrial matrix. Mitochondrial cristae are membrane invaginations and host respiratory chain complexes and adenosine triphosphate (ATP) synthase for oxidative phosphorylation (OXPHOS) that produces ATP and mitochondrial reactive oxygen species (ROS) as byproducts. Optic atrophy protein 1 (OPA1) forms oligomers at cristae junctions. The matrix serves as the site of the tricarboxylic acid (TCA) cycle and mitochondrial deoxyribonucleic acid (mtDNA) replication. (B) The main structural difference between the smooth ER and the rough ER is that the rough ER is covered with ribosomes. (C) MAMs are recognized as a critical platform for the interaction between mitochondria and the ER, with numerous proteins that maintain the structure and function of MAMs playing essential roles.
Credit
Lanshu Xiao, Yao Wei, Yiping Qin, Bianqin Guo
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