20 articles
ADP/ATP translocase 4
ADP/ATP translocase 4 (ANT4, SLC25A31, AAC4, SFEC) is a testis-specific mitochondrial ADP/ATP antiporter essential for mouse spermatogenesis, conserved in mammals and anole lizard, and upregulated in some cancers.
Adrenodoxin reductase
Adrenodoxin reductase (FDXR, EC 1.18.1.6) is a monomeric FAD flavoprotein on the inner mitochondrial membrane that transfers electrons from NADPH via adrenodoxin to mitochondrial cytochrome P450 enzymes, enabling steroid hormone biosynthesis; FDXR mutations cause mitochondrial neuropathy.
Alternative oxidase
Alternative oxidase (AOX), encoded by Aox1/AOX1-type nuclear genes, is a cyanide-resistant mitochondrial terminal oxidase in plants, some fungi, and protists that oxidizes ubiquinol, reduces oxygen to water without proton pumping, and drives thermogenesis and stress tolerance.
Cholesterol side-chain cleavage enzyme
Cholesterol side-chain cleavage enzyme, also called P450scc or cholesterol desmolase, is a mitochondrial enzyme that converts cholesterol to pregnenolone, the first and rate-limiting step of steroid hormone synthesis.
Essential MCU regulator, mitochondrial
Essential MCU regulator, mitochondrial (EMRE, formerly C22orf32) is a 10 kDa single-pass inner mitochondrial membrane protein, metazoan-specific, required for MCU-mediated calcium uptake and proposed to bridge MICU1/2 to the MCU pore.
Glycine cleavage system
The glycine cleavage system, or glycine decarboxylase complex, is a mitochondrial enzyme system that breaks down glycine into carbon dioxide, ammonia, and one-carbon units, and defects in it cause nonketotic hyperglycinemia.
Long-chain-fatty-acid—CoA ligase
Long-chain-fatty-acid—CoA ligase (ACSL, long-chain acyl-CoA synthetase) activates C12-C20 fatty acids to acyl-CoA via ATP and CoA. Five mammalian isoforms (ACSL1, 3, 4, 5, 6) differ in substrate preference, location, and roles in ferroptosis and cancer.
Mitochondria associated membranes
Mitochondria associated membranes (MAMs, MERCs), ER–mitochondria contact sites 10–50 nm apart tethered by IP3R–GRP75–VDAC1 and mitofusins, mediating calcium transfer, lipid exchange, autophagy, and disease-linked signaling.
Mitochondrial calcium uniporter
Mitochondrial calcium uniporter (MCU, mtCU): Ca2+-selective ion channel of the inner mitochondrial membrane; DXXE selectivity filter, MICU1/2 gatekeeping, EMRE core subunit; inhibited by Ru360 and Ru265.
Mitochondrial carrier
Mitochondrial carriers, the SLC25A family, are transport proteins that move metabolites across the inner mitochondrial membrane; with 53 human members, it is the largest human solute transporter family.
Mitochondrial Membrane Potential
Mitochondrial membrane potential (ΔΨm) is the voltage across the inner mitochondrial membrane generated by proton pumping at respiratory complexes I, III, and IV. Measured with cationic dyes TMRM, TMRE, rhodamine 123, and JC-1 following the Nernst equation; reports respiratory chain activity and apoptosis.
Mitochondrial permeability transition pore
Mitochondrial permeability transition pore (mPTP, PTP): a high-conductance inner mitochondrial membrane channel passing solutes up to 1.5 kDa, opened by calcium overload, inhibited by cyclosporin A via cyclophilin D; its exact molecular composition remains debated.
Mitochondrial respirasome
The mitochondrial respirasome is a supercomplex of respiratory chain complexes I, III, and IV in the inner mitochondrial membrane, with a mass of about 1.7 megadaltons.
Plastoquinone
Plastoquinone (PQ, PQ-9), a 2,3-dimethyl-nonaprenyl benzoquinone in chloroplast thylakoid membranes, carries two electrons and two protons from photosystem II to cytochrome b6f and signals redox state; discovered by Kofler, rediscovered by Crane.
Pyruvate carboxylase
Pyruvate carboxylase (PC, EC 6.4.1.1), pyruvic carboxylase, is a biotin-dependent mitochondrial tetrameric enzyme converting pyruvate to oxaloacetate for gluconeogenesis, lipogenesis, and insulin secretion; PC gene mutations cause autosomal recessive pyruvate carboxylase deficiency.
Pyruvate dehydrogenase complex
Pyruvate dehydrogenase complex (PDC, PDHc): mitochondrial multi-enzyme assembly (E1, E2, E3, 5-12 MDa) converting pyruvate to acetyl-CoA, CO2, and NADH; regulated by PDK/PDP phosphorylation; deficient in PDC deficiency and dysregulated in cancer.
Q cycle
Q cycle: Mitchell's 1975 mechanism for cytochrome bc1 (complex III) and b6f complexes, in which bifurcated quinol oxidation at the Qo site and quinone recycling at the Qi site pump protons to build a proton motive force.
Steroidogenic acute regulatory protein
StAR (STARD1) is a mitochondrial protein that transports cholesterol across mitochondrial membranes for pregnenolone synthesis, the rate-limiting step of steroidogenesis; mutations cause congenital lipoid adrenal hyperplasia.
Thermogenin
Thermogenin, now called uncoupling protein 1 (UCP1), is a 32 kDa mitochondrial inner-membrane protein of brown and beige adipocytes that leaks protons to generate heat; activated by fatty acids, inhibited by purine nucleotides such as ATP.
Uncoupling protein
Uncoupling proteins (UCP1, UCP2, UCP3, UCP4, UCP5) are mitochondrial inner-membrane carriers that leak protons back to the matrix, producing heat instead of ATP; UCP1 drives brown-fat thermogenesis, activated by fatty acids and superoxide, inhibited by purine nucleotides.