DRP1 (DNM1L)

The master regulator of mitochondrial fission — a cytosolic dynamin-family GTPase that oligomerizes into rings at the outer mitochondrial membrane (OMM), hydrolyzes GTP to mechanically constrict and sever the membrane, and thereby controls the balance between a fragmented and an elongated mitochondrial network. DRP1 opposes mitofusins (OMM fusion) and opa1 (inner-membrane fusion). Its activity is indispensable for normal embryonic development, brain development, and mitochondrial quality control via mitophagy. Hyperactivation of DRP1 — via S-nitrosylation or aberrant phosphorylation — is emerging as a shared pathological thread in alzheimers-disease, parkinsons-disease, and normal brain aging.

Naming note: The gene is officially DNM1L (HGNC 2973); the protein is commonly called DRP1 in the literature. “DLP1” is an earlier synonym. This page uses DRP1 throughout per convention. No pathways/drp1.md exists — if a dedicated mitochondrial-dynamics pathway page is seeded, cross-link from the pathways: frontmatter field.

Identity

Feature	Value
UniProt	O00429 (DNM1L_HUMAN) — Swiss-Prot (manually reviewed)
NCBI Gene	10059
HGNC symbol	DNM1L
Ensembl	ENSG00000087470
Canonical length	736 aa (9 splice variants total; see isoform note below)
MW	~82 kDa
Mouse ortholog	Dnm1l (one-to-one)
Dynamin superfamily	yes; related to dynamin-1 (DNM1), DNM2, and MxA
GenAge (human)	not listed

UniProt lists nine isoforms (O00429-1 through O00429-9) generated by alternative splicing. The canonical UniProt sequence (O00429-1, 736 aa, called “isoform 1” / “HdynIV-WT” / “DLP1F” in UniProt) is the brain-enriched form; UniProt annotation states “Isoform 1 is brain-specific.” The literature commonly refers to this same sequence as “isoform 2” using a different numbering system (DLP1a/DRP1-x01 in NCBI), creating persistent isoform-numbering confusion. Residue numbering on this page follows UniProt canonical (O00429-1, 736 aa) unless noted. Isoform differences cluster in the variable/B-insert domain and may alter receptor preference and regulation.

Domain architecture

N----[GTPase domain]---[middle domain]---[B-insert/variable domain]---[GED]----C
     ~aa 22–302        ~aa 344–489       ~aa 502–569                ~aa 644–735

GTPase domain (G domain, aa ~22–302): Contains G1–G5 motifs for GTP binding and hydrolysis. The dominant-negative K38A substitution (G1 motif) blocks GTP binding and collapses mitochondria into a perinuclear aggregate, freezing the fission cycle ¹. no-fulltext-access — Smirnova 2001 (MBC, not_oa) unverified against full text.
Middle domain / stalk (aa ~344–489): Mediates oligomerization (dimers → tetramers → higher-order rings) and conformational coupling between GTP hydrolysis and membrane constriction.
B-insert / variable domain (aa ~502–569): Metazoan-specific insertion absent in dynamin-1 and yeast Dnm1. Contains sumoylation sites (K532, K558, K568, K594, K606 by UniProt annotation) and is a regulatory hotspot. The brain-specific exon 15/16 splice alternatives are within this domain.
GED / GTPase effector domain (aa ~644–735): Intramolecular contacts with the G domain to stimulate GTP hydrolysis upon self-assembly; C644 is the S-nitrosylation target linked to Alzheimer pathology ².

Receptor-mediated recruitment to the OMM

DRP1 is predominantly cytosolic (~97% at steady state) and must be recruited to the OMM by integral membrane receptors. Four mammalian receptors are established, with distinct contributions:

Receptor	Gene	Notes
MFF	mff	Primary recruitment factor; required for DRP1-dependent fission in HeLa and HCT116 cells ³ no-fulltext-access — Otera 2010 (JCB, not_oa) unverified against full text; cell-line attribution may need correction
MID49	mid49 (MIEF2)	Dynamin-like GTPase receptor; can tether DRP1 without promoting fission — bifunctional
MID51	mid51 (MIEF1)	Related to MID49; recruits and inhibits DRP1 in steady state; nucleotide-sensitive
FIS1	fis1	Required in yeast; mammalian FIS1 contribution to DRP1-dependent fission is disputed — MFF knockdown fully suppresses fission even when FIS1 is intact ³ contradictory-evidence no-fulltext-access

The ER-mitochondria contact site (ERMES equivalent in mammals) is also a spatial organizer: Friedman et al. 2011 showed that ER tubules wrap constricting mitochondria at pre-fission sites, positioning DRP1 rings at the narrowest points before scission occurs ⁴. no-fulltext-access — Friedman 2011 (Science, not_oa) unverified against full text.

Dimension	Status
Pathway conserved in humans?	yes
Phenotype conserved in humans?	yes (EMPF1 — see below)
Replicated in humans?	yes (genetic; EMPF1 patients; ND patient cohorts)

Post-translational modification

PTMs are the primary regulatory layer for DRP1 activity; subcellular localization and oligomeric state respond acutely to kinase/phosphatase flux.

Phosphorylation

Site (human, UniProt canonical isoform 1 / brain isoform)	Kinase	Phosphatase	Effect
Ser616	CDK1 (mitotic), PINK1	—	Activates GTPase; promotes translocation to OMM and fission (UniProt O00429, PubMed:18838687, PubMed:21822277) no-fulltext-access — primary source PDFs for Ser616 studies not locally verified
Ser637	PKA (cAMP-dependent), CAMK1	Calcineurin (PPP3CA)	PKA phospho inhibits fission (promotes elongation); calcineurin dephosphorylation activates fission ⁵⁶

Isoform numbering note: Chang & Blackstone 2007 ⁵ used human DRP1 isoform 1 (splice variant 1, NM_012062) and report the PKA site as Ser637 — consistent with UniProt canonical numbering. Cribbs & Strack 2007 ⁶ used rat Drp1 splice variant 1 and report the same site as Ser656 (rat isoform numbering). These are equivalent residues in orthologous proteins. Earlier papers citing “Ser656” in human DRP1 have used isoform 3 numbering; always verify the isoform when comparing across studies. needs-replication — standardized isoform-aware reporting is inconsistent in the literature.

S-nitrosylation

Cys644 (within the GED) undergoes S-nitrosylation under nitrosative stress ². S-nitrosylation increases DRP1 dimerization and GTPase activity, driving excessive fragmentation. Cho et al. 2009 identified elevated S-nitros-DRP1 in postmortem AD patient brains and demonstrated that Aβ1-42 oligomers increase NO production, S-nitrosylate DRP1 at C644, and induce synaptic damage. needs-replication — finding is from a relatively small number of postmortem samples and a single publication; independent replication in patient cohorts is incomplete. no-fulltext-access — Cho 2009 (Science, 10.1126/science.1171091) could not be downloaded despite green OA status; sample sizes and exact mechanism claims unverified against full text.

Other PTMs

Sumoylation: SUMO-1 conjugation stabilizes DRP1 at the OMM; MUL1 (MITOL) and MARCH5 ubiquitinate DRP1 for proteasomal degradation.
O-GlcNAcylation: Enhances GTP-bound active form; promotes cytoplasm-to-mitochondria translocation.
Ubiquitination: MARCH5/MARCHF5-mediated ubiquitination maintains mitochondrial morphology homeostasis.

Loss-of-function phenotypes

Cell culture

Dominant-negative K38A DRP1 expression causes mitochondria to collapse from an elongated network into perinuclear aggregates in mammalian cells ¹. Fission is completely blocked. The same result is produced by MFF knockdown. This provided the first demonstration in mammalian cells that DRP1 is strictly required for mitochondrial fission.

Mouse knockout (in vivo)

Homozygous Dnm1l-null mice die at approximately E11.5 with severely elongated, clustered mitochondria in the placenta and throughout the embryo ⁷. The developmental lethality reflects the requirement for fission during cell division (to partition mitochondria to daughter cells) and during neuronal morphogenesis.

Conditional brain-specific knockout driven by En1-Cre (engrailed 1 — expressed in cerebellum, midbrain, and limb bud, NOT Nestin-Cre) causes cerebellar developmental defects: severely hypoplastic cerebellum (~60% of control area), loss of Purkinje cell layer integrity, and death within 36 hours of birth ⁷. Purkinje cells in En1-DrpKO mice at P0 showed dramatically decreased numbers and failed to form a normal monolayer. The defect is developmental (failed lobulation and Purkinje cell proliferation/differentiation), not progressive post-natal neurodegeneration. This established that DRP1-dependent fission is non-negotiable for cerebellar development in vivo.

Dimension	Status
Pathway conserved in humans?	yes
Phenotype (developmental lethality/cerebellar developmental defects) in humans?	yes — EMPF1 (see below)
Replicated in humans?	yes (genetic)

Human disease: EMPF1

Heterozygous de novo missense mutations in DNM1L cause encephalopathy due to defective mitochondrial and peroxisomal fission 1 (EMPF1; OMIM 614388) — a lethal autosomal dominant disorder ⁸. The index case in Waterham et al. 2007 (NEJM) was a neonate who died at 37 days with brain anomalies, optic atrophy, hypotonia, abnormal very-long-chain fatty acid profile (reflecting peroxisomal fission defect), and giant interconnected mitochondria in cultured fibroblasts. The causative variant (A395D; now mapped to the middle domain / stalk) impaired oligomerization and OMM recruitment. no-fulltext-access — Waterham 2007 (NEJM, not_oa) unverified against full text; age at death and variant details not confirmed from primary source.

Additional pathogenic variants (G362S, R403C, L406S) have since been described; all cluster in the stalk domain and impair self-assembly. DRP1 is also required for peroxisomal fission — DRP1 rings constrict peroxisomes as well as mitochondria — so EMPF1 presents with a combined mitochondrial + peroxisomal morphology defect distinguishable from pure mtDNA or respiratory-chain disorders.

Optic atrophy 5 (OPA5)

A subset of heterozygous DNM1L variants (e.g., E2A, A192E) cause dominantly inherited optic atrophy (OPA5; OMIM 610708) with adult onset, a phenotype that overlaps with opa1-driven OPA1. Mechanistically distinct from EMPF1: OPA5-associated alleles show altered intracellular localization rather than failed oligomerization.

Hyperactivation in neurodegeneration

Alzheimer’s disease

S-nitrosylation at Cys644 (SNO-DRP1) is elevated in postmortem AD brains; Aβ1-42 drives this via nNOS/eNOS-dependent NO production ².
Ser616 is hyperphosphorylated in AD patient neurons; ERK1/2 and CDK5 (aberrantly activated in AD) both phosphorylate this site. unsourced — independent primary source for CDK5 at Ser616 in AD neurons not yet cited on this page; requires literature review.
Net effect: excessive DRP1 hyperactivation → mitochondrial fragmentation → decreased ATP production → synaptic loss → neuronal death.
DRP1 hyperactivation in AD is considered a feedforward loop: mitochondrial dysfunction → elevated ROS → further NO and kinase activation → more fission.

Parkinson’s disease

PINK1 phosphorylates DRP1 at Ser616, and independently at Ser637 (isoform-dependent), with the net effect of promoting fission and facilitating mitophagy via DRP1-dependent isolation ⁶. See pink1-parkin-pathway for the full circuit.
Alpha-synuclein aggregates (Lewy body precursors; see alpha-synuclein) interact with DRP1 and increase fission; mutant A53T alpha-syn drives DRP1 hyperactivation. unsourced — primary citation needed for alpha-syn/DRP1 direct interaction.
LRRK2 (16 experiments in UniProt PPI data) — functional interaction with DRP1 at mitochondria; mechanistic link under investigation. no-mechanism

Huntington’s disease

DRP1 Ser616 is hyperphosphorylated by CDK5 in striatal neurons in HD models; DRP1 inhibition or S637 phosphomimic expression reduces mitochondrial fragmentation and partially rescues neurodegeneration in HD mouse models. unsourced — dedicated primary citation needed; flag for next lint pass.

DRP1 in the fission–fusion cycle and mitophagy

Mitochondria undergo constant cycles of fission and fusion that serve quality-control functions ⁹:

Fusion redistributes mtDNA and metabolites across the network; favored in healthy, energized mitochondria (high Δψm) — driven by mitofusins (OMM) + opa1 (inner membrane).
Fission (DRP1-mediated) isolates a daughter organelle. A critically low Δψm prevents inner-membrane re-fusion (by inhibiting OPA1 long-form), trapping the dysfunctional fragment.
The isolated fragment accumulates PINK1, which phospho-activates parkin, triggering ubiquitin-mediated mitophagy (see pink1-parkin-pathway).

Consequence: DRP1 is required for the segregation step upstream of mitophagy; its loss impairs not just network dynamics but mitochondrial quality control at the organellar level. In aged tissues where mitophagic flux is already declining, reduced DRP1 activity may paradoxically protect (by preventing fragmentation) while impairing clearance — a context-dependence that complicates intervention design. contradictory-evidence

Dimension	Status
Fission-before-mitophagy pathway conserved in humans?	yes
Phenotype (impaired mitophagy upon DRP1 loss) in humans?	partial — human genetic evidence from EMPF1; mitophagy flux not directly measured
Replicated in humans?	in-progress

Aging relevance

In aged post-mitotic neurons and cardiomyocytes, the balance shifts toward fusion (elongated networks), attributed to decreased DRP1 expression or activity with age. Whether this shift is compensatory (protecting from fragmentation-driven apoptosis) or deleterious (impairing mitophagy) remains unresolved. contradictory-evidence
DRP1 Ser616/Ser637 phosphorylation ratios change with age in mouse brain, reflecting shifts in CDK1 and PKA activity. unsourced — primary citation needed for age-dependent phospho-ratio data.
Mitofusin degradation via PINK1/Parkin requires upstream DRP1-mediated fission — loss of DRP1 in aged neurons would therefore block the mitophagy isolation step irrespective of PINK1/Parkin activity, creating a convergent bottleneck. See mitofusins for the complementary perspective.
Hyperactivation of DRP1 (SNO-DRP1, pSer616) in AD/PD/HD represents the opposite failure mode: excessive fission depletes mitochondrial reserve capacity and is directly linked to neuronal energetic crisis.

Therapeutic angle: Mdivi-1 and the specificity problem

Mdivi-1 (mitochondrial division inhibitor 1) was identified as a mitochondrial fission inhibitor in a yeast chemical screen and has been widely used as a tool compound to study fission in hundreds of studies. It was reported to inhibit the yeast Dnm1 GTPase; it was subsequently assumed to inhibit mammalian DRP1 by the same mechanism.

Critical caveat (Bordt et al. 2017): Mdivi-1 is a reversible Complex I inhibitor that suppresses mitochondrial ROS production independently of DRP1 at the concentrations used in most cell biology experiments (25–100 µM) ¹⁰. Against recombinant self-assembling human DRP1, Mdivi-1 inhibits GTPase activity with a Ki > 1.2 mM — no significant inhibition is observed at the 25–50 µM concentrations routinely used experimentally. Bordt et al. further showed that Complex I-dependent O₂ consumption is inhibited at these same concentrations in a DRP1-independent manner (confirmed in Drp1 KO MEFs). The observed “DRP1 inhibition” phenotypes in published studies may partly or wholly reflect altered redox state and ROS attenuation from Complex I inhibition rather than specific DRP1 blockade. This casts doubt on the specificity of conclusions drawn from Mdivi-1 studies that did not include DRP1-knockout or genetic controls.

Implications:

Mdivi-1 data in the published literature should be treated with caution unless paired with DRP1 genetic perturbation (siRNA, dominant-negative, or conditional KO).
No clean, cell-permeable, specific DRP1 GTPase inhibitor with validated on-target evidence exists as of early 2026. dose-response-unclear
Dynasore (a pan-dynamin GTPase inhibitor) has similar specificity problems.
P110 peptide (designed to block DRP1–FIS1 interaction) has been used in some cardiac/ND models; selectivity profile is better but not fully characterized. no-mechanism

Cross-references

mitofusins — OMM fusion GTPases; antagonize DRP1; both are Parkin substrates
opa1 — inner-membrane fusion GTPase; OPA1 long-form inhibition by DRP1-mediated depolarized fragments triggers mitophagy isolation
pink1-parkin-pathway — DRP1 fission step is upstream prerequisite for PINK1/Parkin-mediated mitophagy
mitophagy — fission-dependent selective autophagy of depolarized mitochondria
mff — primary DRP1 OMM receptor (mammalian)
fis1 — OMM receptor; mammalian role disputed vs yeast
mid49 — MID49/MIEF2; bifunctional DRP1 recruiter/inhibitor
mid51 — MID51/MIEF1; ADP-binding allosteric DRP1 receptor
alpha-synuclein — interacts with DRP1; promotes fission in PD models
parkinsons-disease — DRP1 hyperactivation via PINK1/LRRK2/alpha-syn convergence
alzheimers-disease — SNO-DRP1; Aβ-driven fragmentation
mitochondrial-dysfunction hallmark — fragmentation as readout and driver
disabled-macroautophagy hallmark — impaired fission blocks mitophagy isolation step
mitochondrial-biogenesis (verified) — fission/fusion/biogenesis are co-regulated

Limitations and gaps

Gap	Tag	Notes
No GenAge entry	—	DNM1L is not in GenAge Build 21; aging relevance is based on functional evidence, not genetic longevity association
Mdivi-1 specificity	`#gap/contradictory-evidence`	Most published Mdivi-1 studies predate the Bordt 2017 Complex I finding; effect attribution is uncertain without genetic controls
CDK5/SNO-DRP1 claims in AD/HD	`#gap/unsourced`	Specific primary citations for CDK5-at-Ser616 in AD neurons and for alpha-syn/DRP1 direct interaction not yet added; flag for lint pass
Age-dependent phospho-ratio data	`#gap/unsourced`	Age-vs-youth DRP1 pSer616/pSer637 ratio in mouse brain — primary source citation missing
isoform-aware residue numbering	`#gap/needs-replication`	Ser616 and Ser637 numbering is isoform-specific; conflation across isoforms is common in the literature
Fis1 mammalian role	`#gap/contradictory-evidence`	FIS1 contribution to DRP1 recruitment in mammals is disputed; complete suppression by MFF knockdown alone suggests FIS1 is minor or redundant
P110 peptide mechanism	`#gap/no-mechanism`	DRP1–FIS1 inhibitory peptide studied in cardiac ischemia; selectivity/mechanism not fully characterized
Human aging flux data	`#gap/needs-human-replication`	DRP1 activity changes with age primarily from rodent studies; human data are largely postmortem or in vitro
Partially unverifiable primary sources	`#gap/no-fulltext-access`	Smirnova 2001 (MBC), Otera 2010 (JCB), Friedman 2011 (Science), Waterham 2007 (NEJM) are not_oa closed-access. Cho 2009 (Science) is green OA but download failed. PDFs verified: Bordt 2017, Wakabayashi 2009, Cribbs-Strack 2007, Chang-Blackstone 2007, Twig 2008.

Footnotes

doi:10.1091/mbc.12.8.2245 · smirnova-2001-drp1-fission-mammalian · in-vitro (dominant-negative K38A transfection, COS-7 cells) · model: COS-7 mammalian cells · Crossref-confirmed title: “Dynamin-related Protein Drp1 Is Required for Mitochondrial Division in Mammalian Cells” ↩ ↩²
doi:10.1126/science.1171091 · cho-2009-drp1-s-nitrosylation-ad · in-vitro + postmortem human brain · n=postmortem AD brains (small series) · in-vitro + observational · model: Abeta1-42-treated neurons + human AD postmortem · Crossref-confirmed title: “S-Nitrosylation of Drp1 Mediates β-Amyloid-Related Mitochondrial Fission and Neuronal Injury” · Verify sample sizes against primary source needs-replication ↩ ↩² ↩³
doi:10.1083/jcb.201007152 · otera-2010-mff-drp1-recruitment · in-vitro (siRNA knockdown + live imaging, HeLa/HCT116) · model: human cell lines · Crossref-confirmed title: “Mff is an essential factor for mitochondrial recruitment of Drp1 during mitochondrial fission in mammalian cells” ↩ ↩²
doi:10.1126/science.1207385 · friedman-2011-er-mitochondria-fission · in-vitro (live imaging + EM, COS-7) · model: mammalian cells + correlative EM · Crossref-confirmed title: “ER Tubules Mark Sites of Mitochondrial Division” ↩
doi:10.1074/jbc.C700083200 · chang-blackstone-2007-drp1-pka-cdk1 · in-vitro (32P metabolic labeling + in-vitro PKA phosphorylation, HeLa) · model: human HeLa cells · uses human DRP1 isoform 1 (splice variant 1, NM_012062); PKA site = Ser637 in GED domain · PKA phosphorylation inhibits GTPase activity and mitochondrial fission (Ki mechanism: impairs GED-to-G-domain intramolecular interaction) · verified against PDF ↩ ↩²
doi:10.1038/sj.embor.7401062 · cribbs-strack-2007-drp1-pka-calcineurin · in-vitro (transfection + metabolic 32P labeling, PC12/COS/CV1 cells) · model: rat pheochromocytoma PC12 cells and fibroblasts · Note: uses rat Drp1 splice variant 1; PKA site numbered Ser656 in rat = Ser637 in human isoform 1 · calcineurin identified as the phosphatase via FK506/cyclosporin A inhibitor experiments · verified against PDF ↩ ↩² ↩³
doi:10.1083/jcb.200903065 · wakabayashi-2009-dnm1l-null-mice · in-vivo (Dnm1l-null complete KO and En1-Cre conditional brain KO, mouse) · model: Mus musculus embryonic/neonatal KO · Crossref-confirmed title: “The dynamin-related GTPase Drp1 is required for embryonic and brain development in mice” · complete KO: lethal E11.5 (0/12 viable at E11.5) · En1-DrpKO: dies within 36 h of birth with cerebellar developmental defects and Purkinje cell loss ↩ ↩²
doi:10.1056/NEJMoa064436 · waterham-2007-dnm1l-empf1-nejm · in-vivo + genetics (case report, n=1 proband + fibroblast assays) · model: human neonatal case + primary fibroblasts · Crossref-confirmed title: “A Lethal Defect of Mitochondrial and Peroxisomal Fission” ↩
doi:10.1038/sj.emboj.7601963 · twig-2008-fission-fusion-mitophagy · in-vitro (live imaging + mtPA-GFP photo-activation, INS1 rat beta cells and primary mouse beta cells; COS7 cells for some experiments) · model: pancreatic beta cells (primary and INS1 cell line) · Crossref-confirmed title: “Fission and selective fusion govern mitochondrial segregation and elimination by autophagy” · verified against PDF ↩
doi:10.1016/j.devcel.2017.02.020 · bordt-2017-mdivi1-complex-i · in-vitro (biochemical + cell; neurons, COS-7, MEFs, isolated mitochondria) · model: primary rat cortical neurons + mammalian cell lines + Drp1 KO MEFs · key finding: human Drp1 GTPase Ki > 1.2 mM (no inhibition at 25–100 µM); Complex I respiration inhibited at 25–100 µM in Drp1-independent manner · Crossref-confirmed title: “The Putative Drp1 Inhibitor mdivi-1 Is a Reversible Mitochondrial Complex I Inhibitor that Modulates Reactive Oxygen Species” ↩

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