What Is ATP1A4? Biological Background

ATP1A4 encodes the alpha-4 isoform of the Na+/K+-ATPase catalytic subunit, a member of the P-type ATPase superfamily. Na+/K+-ATPase enzymes are transmembrane ion pumps that use the energy derived from ATP hydrolysis to actively transport three sodium ions out of the cell and two potassium ions into the cell per catalytic cycle, thereby maintaining the electrochemical gradients essential for cell volume regulation, membrane potential, and secondary active transport processes.

Unlike the ubiquitously expressed alpha-1, alpha-2, and alpha-3 isoforms, the alpha-4 subunit encoded by ATP1A4 displays a highly restricted expression pattern, being predominantly found in the testis and, more specifically, in mature spermatozoa. This tissue-restricted distribution suggests a specialized physiological role that is distinct from other alpha isoforms. Studies using animal models have demonstrated that disruption of the alpha-4 subunit leads to severe impairments in sperm motility and male infertility, highlighting its critical importance in reproductive biology.

The protein functions as part of a heterodimeric complex, associating with a beta subunit (and in some contexts a regulatory FXYD subunit) to form the fully functional holoenzyme. The alpha subunit contains the catalytic core, including the phosphorylation site, the ATP-binding domain, and the ion-binding transmembrane segments.

Biochemical Properties of Recombinant Human ATP1A4 Protein

The recombinant form of human ATP1A4 protein (SKU: rp369382) is produced using recombinant expression technology to provide a consistent, research-grade reagent for in vitro studies. Recombinant production allows researchers to obtain the protein in quantities and purity levels not readily achievable from native tissue sources, enabling reproducible experimental results across biochemical, cellular, and structural investigations.

Key biochemical characteristics of the ATP1A4 alpha subunit include its classification as an E1-E2 type ATPase, undergoing conformational changes between two principal states (E1 and E2) coupled to ion binding and phosphorylation/dephosphorylation events. The protein is sensitive to the cardiac glycoside ouabain, which is a classical inhibitor of Na+/K+-ATPase activity and is commonly used in functional assays to confirm pump identity and measure inhibition kinetics. Notably, the alpha-4 isoform may display different ouabain sensitivity compared to alpha-1, a feature that has been exploited in research settings to selectively study alpha-4-specific activity in mixed-isoform systems.

Researchers should note that specific details regarding the exact expression host system, purity grade, buffer formulation, and storage conditions for SKU rp369382 should be confirmed directly from the Aladdin Scientific product datasheet to ensure experimental compatibility.

Research Applications

Recombinant Human ATP1A4 Protein is a versatile tool for a range of research applications in cell biology, reproductive physiology, and biochemistry:

• Ion Transport Studies: The protein can be used in reconstituted systems or biochemical assays to investigate the kinetics of Na+ and K+ transport, ATP hydrolysis rates, and the effects of pharmacological modulators on pump activity.
• Male Infertility Research: Given its restricted expression in the testis and its established role in sperm motility, recombinant ATP1A4 is valuable for studying mechanisms underlying male infertility, including the identification of potential therapeutic targets.
• Enzyme Activity Assays: Researchers can employ the recombinant protein in ATPase activity assays (e.g., colorimetric phosphate release assays) to characterize inhibitors or activators of the alpha-4 isoform specifically.
• Antibody Validation and Immunoassay Development: Recombinant ATP1A4 serves as a positive control antigen for validating antibodies raised against the alpha-4 subunit, supporting Western blot, ELISA, and immunoprecipitation applications.
• Structural and Biophysical Studies: The availability of purified recombinant protein facilitates biophysical characterization techniques such as circular dichroism, intrinsic fluorescence, and interaction studies with partner proteins or small molecules.
• Drug Discovery: As a potential therapeutic target in conditions affecting male fertility, ATP1A4 recombinant protein can support high-throughput screening campaigns for novel modulators.

Handling, Storage, and Quality Considerations

To ensure optimal performance of Recombinant Human ATP1A4 Protein in downstream assays, adherence to recommended handling and storage practices is essential. General best practices for recombinant proteins apply:

• Storage: Store the protein at the temperature specified on the product datasheet (typically −20°C or −80°C for long-term storage). Avoid repeated freeze-thaw cycles, which can lead to protein aggregation and loss of activity.
• Aliquoting: Upon first thaw, prepare single-use aliquots to minimize freeze-thaw cycles and preserve protein integrity over time.
• Reconstitution: If supplied in lyophilized form, reconstitute according to the manufacturer's instructions using an appropriate buffer. Allow the vial to equilibrate to room temperature before opening.
• Quality Control: Aladdin Scientific recombinant proteins are subject to quality control testing. Researchers should consult the Certificate of Analysis (CoA) supplied with the product for lot-specific purity, concentration, and activity data.
• Experimental Controls: Include appropriate positive and negative controls in all assays. When assessing ATPase activity, use validated inhibitors such as ouabain as functional controls to confirm protein activity.

For specific storage conditions, buffer composition, concentration, and expiry information for SKU rp369382, always refer to the current Aladdin Scientific product datasheet and CoA.