Recombinant Human ME3 Protein: Properties & Research Uses

Recombinant Human ME3 Protein is a mitochondrial, NADP-dependent malic enzyme that catalyzes the oxidative decarboxylation of malate to pyruvate and plays a critical role in cellular energy metabolism and redox balance.

Protein Name

Recombinant Human ME3 Protein

SKU

rp372357

Gene Name

ME3

Enzyme Class

NADP-dependent malic enzyme (mitochondrial)

Catalytic Reaction

Malate + NADP⁺ → Pyruvate + CO₂ + NADPH

Subcellular Localization

Mitochondrial matrix

Research Application

Metabolic research, enzyme activity assays, redox biology

What Is ME3 (Malic Enzyme 3)?

Malic Enzyme 3 (ME3) is a member of the malic enzyme family, which comprises three isoforms in humans: cytosolic NAD-dependent ME1, mitochondrial NADP-dependent ME2, and mitochondrial NADP-dependent ME3. ME3 is encoded by the ME3 gene and is localized to the mitochondrial matrix, where it catalyzes the oxidative decarboxylation of L-malate to pyruvate with the concomitant reduction of NADP⁺ to NADPH. This reaction links the tricarboxylic acid (TCA) cycle to pyruvate metabolism and contributes to mitochondrial NADPH production, which is essential for antioxidant defense and biosynthetic reactions. ME3 requires divalent metal cations—typically Mg²⁺ or Mn²⁺—as cofactors for catalytic activity.

Biological Functions and Significance

ME3 plays several important roles in cellular physiology. First, by producing NADPH within the mitochondria, ME3 supports the glutathione and thioredoxin antioxidant systems, helping cells manage reactive oxygen species (ROS). Second, the pyruvate generated by ME3 can enter the TCA cycle or serve as a substrate for other metabolic pathways, making ME3 an important node in central carbon metabolism. Third, ME3 activity has been implicated in metabolic reprogramming associated with proliferating cells, including cancer cells, where altered malic enzyme expression may confer metabolic advantages. Research into ME3 therefore spans energy metabolism, oxidative stress biology, and oncometabolism.

Research Applications of Recombinant Human ME3 Protein

Recombinant Human ME3 Protein (Aladdin Scientific SKU: rp372357) is suitable for a range of in vitro research applications:

• Enzyme Activity Assays: Measurement of NADP-dependent malic enzyme activity by monitoring NADPH production spectrophotometrically at 340 nm.
• Biochemical Characterization: Studies of substrate specificity, cofactor requirements, inhibition kinetics, and allosteric regulation.
• Protein–Protein Interaction Studies: Co-immunoprecipitation, pull-down assays, or surface plasmon resonance to identify interaction partners.
• Antibody Validation: Use as a positive control antigen in Western blot, ELISA, or immunohistochemistry workflows.
• Structural Biology: As a standard or reference in mass spectrometry and other structural analyses.
• Drug Discovery: Screening of small-molecule inhibitors or activators targeting ME3 enzymatic activity.

Researchers in metabolic disease, cancer biology, and redox biology will find this recombinant protein particularly valuable for establishing reliable, reproducible experimental systems.

Storage, Handling, and Quality Considerations

To ensure optimal performance of Recombinant Human ME3 Protein, users should observe the following general best practices for recombinant proteins:

• Storage: Store at −80 °C for long-term stability. Avoid repeated freeze–thaw cycles, which can compromise protein integrity and enzymatic activity.
• Aliquoting: Upon first thaw, prepare single-use aliquots to minimize freeze–thaw degradation.
• Buffer Conditions: Maintain the protein in its supplied formulation buffer. Confirm compatibility with downstream assay buffers before dilution.
• Purity and Identity: Verify purity by SDS-PAGE or size-exclusion chromatography, and confirm identity by Western blot using an anti-ME3 antibody.
• Activity Validation: Where enzymatic activity data are required, perform a standard NADPH generation assay prior to use in novel experimental systems.

Always consult the specific product datasheet for lot-specific purity, concentration, and activity data.

Frequently asked questions

What is the enzymatic function of ME3?

ME3 (Malic Enzyme 3) catalyzes the oxidative decarboxylation of L-malate to pyruvate, reducing NADP⁺ to NADPH in the process. This reaction occurs in the mitochondrial matrix and requires divalent metal ion cofactors such as Mg²⁺ or Mn²⁺.

How does ME3 differ from ME1 and ME2?

ME1 is a cytosolic, NAD-dependent isoform, while ME2 and ME3 are both mitochondrial and NADP-dependent. ME3 is distinguished from ME2 primarily by its gene locus and subtle differences in tissue expression patterns and regulatory properties, although both share the same mitochondrial NADP-dependent catalytic mechanism.

What are the recommended storage conditions for Recombinant Human ME3 Protein (rp372357)?

The protein should be stored at −80 °C for long-term preservation. Repeated freeze–thaw cycles should be avoided to maintain protein integrity and activity. Single-use aliquots are recommended after the initial thaw. Always refer to the product-specific datasheet for precise formulation and storage guidance.

Can Recombinant Human ME3 Protein be used as a positive control in Western blot?

Yes. Recombinant Human ME3 Protein is well-suited as a positive control antigen in Western blot, ELISA, and related immunodetection assays, enabling validation of anti-ME3 antibody specificity and sensitivity.

What research areas benefit most from studying ME3?

ME3 research is particularly relevant to cancer metabolism, mitochondrial biology, oxidative stress, and central carbon metabolism. Because ME3 generates mitochondrial NADPH and links malate to pyruvate, it is of interest in studies of metabolic reprogramming, antioxidant capacity, and energy homeostasis.

References

1. Chang GG, Tong L. Structure and function of malic enzymes, a new class of oxidative decarboxylases. Biochemistry. 2003;42(44):12721-12733. doi:10.1021/bi035251+
2. Loeber G, Dworkin MB, Infante A, Ahorn H. Characterization of cytosolic malic enzyme in human tumor cells. FEBS Lett. 1994;344(2-3):181-186.
3. Jiang P, Du W, Wu M. Regulation of the pentose phosphate pathway in cancer. Protein Cell. 2014;5(8):592-602.
4. Aladdin Scientific. Recombinant Human ME3 Protein, SKU rp372357. Product Datasheet.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.