All articles starting with M

Mitochondrial DNA

Mitochondrial DNA (mtDNA): the ~16,569 bp circular, maternally inherited multicopy genome of mitochondria; 37 genes, a variant genetic code, a germline bottleneck, and links to MELAS, LHON, and MERRF disease.

Mitochondrial DNA depletion syndrome

Mitochondrial DNA depletion syndrome is a group of inherited disorders in which cells contain too few copies of mitochondrial DNA, caused by autosomal recessive variants in nuclear genes.

Mitochondrial DNA-associated Leigh syndrome

Mitochondrial DNA-associated Leigh syndrome spectrum (mtDNA-LSS, maternally inherited Leigh syndrome, MILS): Leigh syndrome caused by mtDNA variants, most often m.8993T>G/C in MT-ATP6, with heteroplasmy-driven severity and supportive care only.

Mitochondrial encephalomyopathy

Mitochondrial encephalomyopathy is a mitochondrial disease in which defective respiratory-chain energy production causes both nervous-system and skeletal-muscle disease, covering the classic syndromes MELAS, MERRF, Kearns-Sayre, NARP, and MNGIE.

Mitochondrial Eve

Mitochondrial Eve is the matrilineal most recent common ancestor of all living humans, defined by maternally inherited mitochondrial DNA, estimated from the 1987 Cann, Stoneking, and Wilson Nature study to have lived roughly 100,000-200,000 years ago, probably in Africa.

Mitochondrial fission

Mitochondrial fission, division of a mitochondrion into daughters, is driven by the Drp1/DNM1L GTPase with OMM receptors Mff, MiD49/51 and Fis1 at ER contact sites; distinct from fusion and from Drp1-independent fission pathways.

Mitochondrial fusion

Mitochondrial fusion, the merging of two mitochondria via MFN1/MFN2 (outer membrane) and OPA1 (inner membrane) GTPases, enables content mixing, mtDNA maintenance, quality control, and is disrupted in optic atrophy and CMT2A.

Mitochondrial Genes

Mitochondrial genes are genes on mitochondrial DNA (mtDNA), the maternally inherited, non-recombining, fast-mutating genome of mitochondria; in humans they encode 13 OXPHOS subunits, 2 rRNAs, and 22 tRNAs.

Mitochondrial hypertrophic cardiomyopathy with lactic acidosis due to MTO1 deficiency

Mitochondrial hypertrophic cardiomyopathy with lactic acidosis due to MTO1 deficiency, also known as combined oxidative phosphorylation deficiency 10 (COXPD10), is a rare autosomal recessive mitochondrial disorder.

Mitochondrial import inner membrane translocase subunit TIM22

TIM22 (TIMM22) is the voltage-gated pore-forming core subunit of the mitochondrial inner membrane TIM22 carrier translocase, homologous to Tim17/Tim23, which inserts multispanning metabolite carriers and related proteins into the inner membrane using the membrane potential.

Mitochondrial import receptor subunit Tom22

Tom22 (TOM22_YEAST, P49334), the central receptor subunit of the mitochondrial TOM import complex; binds preproteins on both membrane sides, stabilizes the Tom40 pore dimer, and is conserved across all eukaryotes.

Mitochondrial import receptor subunit Tom6

Tom6 (TOMM6, TOM6) is a small single-pass α-helical subunit of the mitochondrial TOM protein-import complex that stabilizes Tom40, promotes tetramerization, and is conserved in opisthokonts and plants.

Mitochondrial inner membrane i-AAA protease complex subunit Mgr1

Mgr1 (YCL044C), also Mgr1p, is a Saccharomyces cerevisiae mitochondrial inner membrane adaptor subunit of the Yme1 i-AAA protease complex, required for full protease activity, substrate binding, and growth without mtDNA.

Mitochondrial inner membrane protease subunit 2

IMMP2L (UniProt Q96T52), the human mitochondrial inner membrane protease subunit 2, is a serine protease subunit of the IMP complex with IMMP1L, cleaving sorting signals from cytochrome c1 and GPD2; yeast ortholog Imp2; linked to Tourette syndrome.

Mitochondrial inner membrane translocase complex, subunit Tim23

Tim23 (human gene TIMM23) is a core subunit of the TIM23 presequence translocase of the mitochondrial inner membrane, essential for importing presequence-containing proteins; a 2023 structure showed Tim17 forms the channel instead.

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 membrane protein-associated neurodegeneration

MPAN (NBIA4) is an ultra-rare autosomal recessive neurodegenerative disorder caused by C19orf12 mutations, with brain iron accumulation, spasticity, dystonia, cognitive decline, and optic atrophy, onset usually in childhood.

Mitochondrial myopathy

Mitochondrial myopathy: muscle disease from primary respiratory chain dysfunction, causing fatigue, weakness, exercise intolerance, often PEO; mtDNA or nuclear genes, heteroplasmy threshold, ragged-red fiber biopsy, supportive treatment.

Mitochondrial myopathy and sideroblastic anemia

Mitochondrial myopathy and sideroblastic anemia, also called myopathy, lactic acidosis, and sideroblastic anemia (MLASA), is a rare autosomal recessive mitochondrial disorder of muscle and bone marrow.

Mitochondrial myopathy with reversible cytochrome C oxidase deficiency

Mitochondrial myopathy with reversible cytochrome C oxidase deficiency, also called benign COX deficiency or reversible infantile respiratory chain deficiency (RIRCD), is a rare maternally inherited mitochondrial myopathy caused mainly by the homoplasmic MT-TE m.14674T>C mutation, causing severe infantile hypotonia and lactic acidosis with spontaneous recovery by age 2 to 3 years.

Mitochondrial neurogastrointestinal encephalomyopathy

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by TYMP gene mutations, first described in 1976, marked by digestive dysmotility and neurological decline.

Mitochondrial neurogastrointestinal encephalopathy syndrome

MNGIE syndrome, also called thymidine phosphorylase deficiency, is a rare autosomal recessive TYMP-related mitochondrial DNA depletion disease causing gastrointestinal dysmotility, cachexia, ophthalmoplegia, neuropathy, and leukoencephalopathy, with onset around age 18 and mean death at 37 years.

Mitochondrial outer membrane permeabilization

Mitochondrial outer membrane permeabilization (MOMP) is the crucial event in the intrinsic apoptosis pathway where the outer membrane becomes permeable, allowing soluble proteins to enter the cytosol.

Mitochondrial outer membrane translocase complex, subunit Tom5

Tom5, a ~50-amino-acid single-pass subunit of the mitochondrial TOM complex, links import receptors to the Tom40 general import pore via an acid chain and stabilizes the complex; nonessential in yeast, structurally resolved in the human TOM dimer.

Mitochondrial outer membrane translocase complex, subunit Tom70

Tom70, historically named MAS70 in yeast, is a receptor subunit of the TOM complex that recognizes hydrophobic mitochondrial precursor proteins, especially inner membrane metabolite carriers.

Mitochondrial outer membrane transport complex protein Metaxin 1/3

Metaxin 1/3 (IPR017410) is a protein family of mitochondrial outer membrane transport complex proteins, including human MTX1 (Metaxin-1, mitochondrial outer membrane import complex protein 1) and MTX3, SAM-complex components required for import and assembly of beta-barrel proteins such as Tom40 and VDAC.

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 processing peptidase

Mitochondrial processing peptidase (MPP, EC 3.4.24.64) is a matrix metalloprotease heterodimer (α-MPP/β-MPP; PMPCA/PMPCB) that cleaves presequences from most mitochondrial precursor proteins, with MIP removing octapeptides in two-step maturation.

Mitochondrial protein import

Mitochondrial protein import: transport of nuclear-encoded proteins into mitochondria via TOM, TIM23, TIM22, SAM, and MIA translocases; over 99% of the roughly 1,500 human mitochondrial proteins are imported, driven by presequences, membrane potential, and the mtHsp70 motor.