NME3 Human, Active
Description
Introduction to NME3 Human, Active
NME3 (Non-Metastatic Cells 3) is a mitochondrial outer-membrane protein with nucleoside diphosphate kinase (NDPK) activity, playing dual roles in cellular metabolism and organelle dynamics. Its active form (NME3 Human, Active) is critical for mitochondrial fusion, energy metabolism, and hypoxia-induced mitophagy. Structural studies reveal a 169-amino-acid polypeptide (22–169 residues) with a molecular mass of 19.1 kDa, expressed as a hexamer in E. coli for recombinant production .
Role in Mitochondrial Dynamics and Fusion
NME3 interacts with mitofusins (MFN1/2) to regulate mitochondrial fusion, independent of its NDP kinase activity. Key findings:
Functional Duality
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Structural Role: Stimulates fusion by tethering MFN1/2 through oligomerization. The E40D/E46D mutant (reduced oligomerization) fails to rescue fusion .
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Catalytic Role: Supports ATP production via GTP synthesis, essential for cell survival under glucose deprivation .
| Mutant | Fusion Rescue | ATP Production | Source |
|---|---|---|---|
| Wild-Type (WT) | Yes | Yes | |
| H135Q (catalytic-dead) | Yes | No | |
| E40D/E46D (oligomerization-deficient) | No | N/A |
Catalytic Activity and Energy Metabolism
NME3’s NDP kinase activity converts nucleoside diphosphates (NDPs) to triphosphates (NTPs), supplying GTP for mitochondrial processes. Notably:
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Glucose Starvation: WT NME3 restores ATP production in patient cells, while H135Q fails, highlighting its metabolic role .
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Hypoxia-Induced Mitophagy: H135-dependent histidine phosphorylation, not NDPK activity, stabilizes DRP1 against MUL1-mediated ubiquitination .
Role in Hypoxia-Induced Mitophagy
Under hypoxic stress, NME3 recruits DRP1 to mitochondria via phosphatidic acid (PA) binding, enabling mitophagy. Key mechanisms:
| Component | Function | Dependency | Source |
|---|---|---|---|
| NME3 (H135) | Binds PA, recruits DRP1 | PA-dependent, H135 | |
| MUL1 E3 ligase | Ubiquitinates DRP1 in NME3-deficient cells | NME3-independent |
Mechanistic Pathway:
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Hypoxia → PA accumulation on MOM.
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NME3 binds PA, recruits DRP1.
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Active DRP1 evades MUL1-mediated degradation.
Peroxisomal Localization and Function
NME3 localizes to peroxisomes, influencing their morphology and plasmalogen synthesis. Key findings:
Pathological Implications
A homozygous initiation-codon mutation in NME3 causes congenital hypotonia, hypoventilation, and cerebellar dysfunction. Patient fibroblasts exhibit:
Product Specs
NME3, also known as Non-Metastatic Cells 3, may play a role in suppressing metastasis. Studies have shown lower levels of NME3 in highly metastatic cells compared to cells with lower metastatic potential. This protein is involved in essential cellular processes such as nucleoside triphosphate synthesis, apoptosis induction, and hematopoiesis. NME3 expression is observed during the early stages of myeloid differentiation in highly purified CD34+ cells.
Recombinant human NME3, expressed in E. coli, is a single, non-glycosylated polypeptide chain. This protein consists of 169 amino acids (with amino acids 22-169 present) and has a molecular weight of 19.1 kDa. A 21 amino acid His tag is fused to the N-terminus of NME3. Purification is achieved using proprietary chromatographic techniques.
The NME3 solution is provided at a concentration of 0.5 mg/ml. The solution is composed of 50% glycerol, 20mM Tris-HCl buffer (pH 8.0), 0.1M NaCl, and 2mM DTT.
For short-term storage (2-4 weeks), the NME3 solution can be stored at 4°C. For extended storage, it is recommended to freeze the solution at -20°C. Adding a carrier protein (0.1% HSA or BSA) is advisable for long-term storage. To maintain the integrity of the protein, avoid repeated cycles of freezing and thawing.
Analysis by SDS-PAGE has determined the purity to be greater than 95.0%.
The specific activity is measured as the amount of enzyme required to convert 1.0 micromole of ATP and TDP to ADP and TTP per minute. This reaction occurs at pH 7.5 and 25°C in a coupled system with pyruvate kinase (PK) and lactate dehydrogenase (LDH). NME3 exhibits a specific activity greater than 150 units/mg.
Nucleoside diphosphate kinase 3, c371H6.2, DR-nm23, KIAA0516, NDPK-C, NDPKC, NM23-H3, NM23H3.
MGSSHHHHHH SSGLVPRGSH MERTFLAVKP DGVQRRLVGE IVRRFERKGF KLVALKLVQA SEELLREHYA ELRERPFYGR LVKYMASGPV VAMVWQGLDV VRTSRALIGA TNPADAPPGT IRGDFCIEVG KNLIHGSDSV ESARREIALW FRADELLCWE DSAGHWLYE
Product Science Overview
NME3 Human Recombinant is produced in E. coli and is a single, non-glycosylated polypeptide chain containing 169 amino acids (22-169 a.a.) with a molecular mass of 19.1 kDa . The recombinant protein is fused to a 21 amino acid His tag at the N-terminus and is purified using proprietary chromatographic techniques . The formulation typically includes 50% glycerol, 20 mM Tris-HCl buffer (pH 8.0), 0.1 M NaCl, and 2 mM DTT .
NME3 is essential for the synthesis of nucleoside triphosphates, which are vital for various cellular functions . The specific activity of NME3 is defined as the amount of enzyme that converts 1.0 µmole each of ATP and TDP to ADP and TTP per minute at pH 7.5 at 25°C in a coupled system with PK/LDH . This activity is greater than 150 units/mg .
NME3 is involved in several critical cellular processes:
- Metastasis Suppression: NME3 is a possible suppressor of metastasis, with lower levels observed in highly metastatic cells .
- Apoptosis Induction: NME3 plays a role in the induction of apoptosis, a process of programmed cell death that is essential for maintaining cellular homeostasis .
- Hematopoiesis: NME3 is crucial for hematopoiesis, the process of forming new blood cells .
