Recombinant Human MAPK4 Protein: Properties & Applications

Recombinant Human MAPK4 Protein is a bacterially or eukaryotically expressed form of the atypical mitogen-activated protein kinase 4 (ERK4) that enables researchers to investigate its unique non-canonical signaling mechanisms, substrate interactions, and potential roles in disease-relevant pathways.

Protein Name

Recombinant Human MAPK4 (ERK4) Protein

Gene Name

MAPK4 (also known as ERK4, p63-MAPK)

Protein Family

Atypical MAP kinase family (lacks TEY activation motif; contains SEG motif)

Primary Research Application

Kinase activity assays, protein-protein interaction studies, drug discovery screening

Biological Relevance

Implicated in cell cycle regulation, cytoskeletal organization, and cancer biology

Related SKU

rp372347

What Is MAPK4 and Why Does It Matter?

Mitogen-activated protein kinase 4 (MAPK4), also designated ERK4 or p63-MAPK, is a member of the atypical MAP kinase subfamily. Unlike classical ERK1/2, which bear the canonical TEY dual-phosphorylation activation loop motif, MAPK4 contains a SEG motif in its activation loop, rendering it resistant to activation by conventional MAP kinase cascades.

MAPK4 is ubiquitously expressed in human tissues and has been reported to interact with MAP kinase-activated protein kinase 5 (MK5/PRAK), forming a complex that regulates cytoplasmic-nuclear shuttling of MK5. This interaction is essential for MAPK4-dependent phosphorylation of downstream substrates. Emerging evidence links MAPK4 to cell proliferation, differentiation, and cytoskeletal dynamics, and dysregulated MAPK4 expression has been reported in several cancer types, making it a subject of increasing interest in oncology research.

Biochemical Properties of Recombinant Human MAPK4 Protein

Recombinant Human MAPK4 Protein is produced using recombinant expression systems to deliver a well-characterized, research-grade reagent. Key biochemical features include:

• Activation loop motif: Contains the atypical SEG motif instead of the classical TEY motif, distinguishing MAPK4 from conventional ERK family members.
• Molecular weight: The full-length human MAPK4 protein has an approximate molecular weight in the range consistent with its amino acid composition; the recombinant form may include affinity tags that slightly alter observed molecular weight on SDS-PAGE.
• Interaction partner: Binds MK5 (PRAK) through a docking domain, stabilizing MK5 and promoting its cytoplasmic retention or nuclear export.
• Substrate specificity: Phosphorylates MK5 at its activation loop, enabling downstream signaling; additional substrates are under active investigation.

These properties make Recombinant Human MAPK4 Protein suitable for biochemical characterization, substrate mapping, and inhibitor profiling experiments.

Research Applications

Recombinant Human MAPK4 Protein supports a broad range of research applications:

• Kinase activity assays: Used as the active enzyme component in in vitro kinase assays to measure phosphorylation of peptide or protein substrates, enabling profiling of MAPK4 enzymatic activity and inhibitor screening.
• Protein–protein interaction studies: Employed in co-immunoprecipitation, pull-down, or surface plasmon resonance (SPR) experiments to characterize MAPK4 binding partners, particularly the MK5 interaction.
• Structural biology: Suitable as an antigen or binding partner for crystallography or cryo-EM studies aimed at resolving MAPK4 structure in complex with substrates or inhibitors.
• Antibody validation: Used as a positive control antigen to validate MAPK4-specific antibodies in Western blot, ELISA, or immunofluorescence assays.
• Drug discovery: Serves as a tool reagent in high-throughput screening campaigns targeting MAPK4-MK5 signaling for cancer or metabolic disease indications.

Handling, Storage, and Quality Considerations

To maintain the integrity and activity of Recombinant Human MAPK4 Protein, researchers should observe the following best practices:

• Storage: Store at –80 °C upon receipt for long-term preservation. Avoid repeated freeze-thaw cycles, which can reduce protein activity and cause aggregation.
• Aliquoting: Prepare single-use aliquots before freezing to minimize freeze-thaw degradation.
• Buffer compatibility: Consult the product datasheet for the recommended storage buffer composition; ensure compatibility with downstream assay buffers before use.
• Purity assessment: Recombinant proteins should be assessed by SDS-PAGE and, where applicable, activity assays prior to critical experiments to confirm lot-to-lot consistency.
• Endotoxin levels: For cell-based assays, verify endotoxin specifications to avoid confounding inflammatory responses.

Always refer to the current Aladdin Scientific product datasheet (SKU: rp372347) for lot-specific quality data, including purity, activity, and storage recommendations.

Frequently asked questions

What makes MAPK4 an atypical MAP kinase?

MAPK4 (ERK4) lacks the canonical TEY dual-phosphorylation motif found in classical ERK1/2 and instead carries a SEG motif in its activation loop. This structural difference means MAPK4 cannot be activated by the conventional Ras-Raf-MEK cascade, placing it in the atypical MAP kinase subfamily alongside ERK3.

What is the key signaling interaction of MAPK4?

MAPK4 binds and activates MK5 (also known as PRAK, MAP kinase-activated protein kinase 5) through a direct protein-protein interaction. MAPK4 phosphorylates MK5 at its activation loop, leading to MK5 activation and influencing its subcellular localization. This MAPK4-MK5 axis is considered the primary characterized signaling output of MAPK4.

How should Recombinant Human MAPK4 Protein be used in an in vitro kinase assay?

In a typical in vitro kinase assay, Recombinant Human MAPK4 Protein is incubated with a suitable substrate (such as recombinant MK5 or a validated peptide substrate), ATP, and an appropriate kinase assay buffer containing magnesium ions. Phosphorylation is then detected by radioactive labeling, antibody-based methods (e.g., phospho-specific ELISA), or mass spectrometry. Always consult the product datasheet for specific activity data and recommended assay conditions.

Is Recombinant Human MAPK4 Protein suitable for antibody validation?

Yes. Recombinant Human MAPK4 Protein can serve as a positive control antigen in Western blot, ELISA, and immunofluorescence experiments to confirm the specificity and sensitivity of MAPK4-targeting antibodies. Using a well-characterized recombinant protein ensures that any detected signal corresponds to the correct target.

What diseases or biological processes is MAPK4 associated with?

MAPK4 has been implicated in cell cycle regulation, cytoskeletal organization, and cell migration. Dysregulated MAPK4 expression has been reported in certain cancers, suggesting potential roles in tumor progression. Research is ongoing to clarify the precise pathophysiological contributions of MAPK4 and to evaluate it as a therapeutic target.

References

1. Coulombe P, Meloche S. Atypical mitogen-activated protein kinases: structure, regulation and functions. Biochim Biophys Acta. 2007;1773(8):1376-1387. doi:10.1016/j.bbamcr.2006.11.001
2. Kant S, Schumacher S, Singh MK, et al. Characterization of the atypical MAPK ERK4 and its activation of the MAPK-activated protein kinase MK5. J Biol Chem. 2006;281(46):35511-35519. doi:10.1074/jbc.M606693200
3. Aladdin Scientific. Recombinant Human MAPK4 Protein (rp372347) Product Datasheet. Aladdin Scientific; [current version].

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