Mitochondrial Markers

Mitochondria are double-membraned organelles responsible for integrating metabolic pathways for energy production and the coordination of cellular stress responses; namely, apoptosis, hypoxia and autophagy. Considered the powerhouses of the cell, mitochondria release chemical energy stored in glucose and other nutrients in a series of exothermic redox reactions. This is enabled by the production of high-energy electron carriers, NADH and FADH. The process of aerobic respiration initiates in the cytosol during glycolysis. Here, glucose is oxidised and split into two pyruvate molecules, producing two ATP and two NADH. Next, pyruvate is transported across both mitochondrial membranes into the luminal matrix space. The following decarboxylation step produces an additional NADH as pyruvate is converted in to acetyl-CoA; an entry-point intermediate within the circular metabolic pathway known as the Kreb’s cycle. The Kreb’s cycle does not directly generate ATP but instead produces GTP, FADH and three more NADH. The availability of reduced NADH and FADH molecules feeds the third stage of respiration, oxidative phosphorylation. The oxidation of NADH and FADH allows electrons to be transferred across a series of enzymatic complexes (I-IV) integrated within the inner mitochondrial membrane. The energy released in this electron transport chain (ETC) is used to pump protons from the matrix into the intermembrane space. This creates an electrochemical gradient across the inner membrane which is harnessed by the membrane-bound ATP synthase complex to drive ATP formation; a phenomenon called chemiosmosis. NADH oxidation occurs at ETC complex I and is responsible for the movement of ten protons into the intermembrane space. Notably, FADH oxidation only powers the transfer of six protons. This is because FADH-derived electrons enter the ETC downstream at complex II, bypassing the proton-pump activity of complex I. Components of ETC enzymatic complexes constitute useful mitochondrial marker proteins as their expression correlates with mitochondrial density and function. These include: NDUFV2, NDUFS1 (complex I); SDHA-D (complex II); BCS1L, UQCRC1 (complex III); COX2, COX7A2L, COXIV (complex IV); and ATP50, ATP5A (ATP synthase). Other marker proteins can be used to interrogate broader aspects of mitochondrial function. For example, in the matrix the chaperone HSP60 and protease CLPP both promote protein quality control, while outer-membrane bound receptors TOM20 and TOM70 facilitate mitochondrial protein import. The multi-functional anion channel VDAC is another marker of the outer mitochondrial membrane. Conformational changes in VDAC activate apoptosis by promoting mitochondrial outer-membrane permeabilisation and subsequent release of pro-apoptotic factors into the cytoplasm. Finally, several marker proteins inform researchers on mitochondrial dynamics and morphology. These include regulators of mitochondrial fusion (mitofusin1/2, OAP1) and fission (FIS1), as well as other modulators of organelle structure and membrane integrity (mitofilin, prohibitin). We offer a wide range of antibodies against mitochondrial markers including AIF antibodies, Galectin 3 antibodies, HIF-1 alpha antibodies, p53 antibodies, and HSP60 antibodies, that are validated across multiple applications and cover various host species, antibody types, conjugates, and formulations. Changes in the expression or localisation of these proteins can indicate alterations in mitochondrial activity which can be linked to neurodegenerative disorders, cancer or ageing.