Recombinant Human KIF9 Protein: Handling & Application Protocol

Recombinant Human KIF9 Protein is a eukaryotic kinesin-family motor protein produced for use in motility assays, biochemical characterization, and cell biology research requiring a defined, high-purity human KIF9 source.

Product Name

Recombinant Human KIF9 Protein

SKU

rp374502

Protein Family

Kinesin superfamily (KIF9, kinesin-like protein)

Recommended Storage

-80°C for long-term; avoid repeated freeze-thaw cycles

Application Compatibility

Motility assays, biochemical binding studies, cell biology research

Form

Recombinant protein, typically supplied lyophilized or in carrier solution

Background: KIF9 and Its Biological Role

KIF9 (Kinesin Family Member 9) is a member of the kinesin superfamily of microtubule-based motor proteins. These proteins utilize the energy derived from ATP hydrolysis to transport cargo along microtubule tracks within eukaryotic cells, playing essential roles in intracellular transport, cell division, and cytoskeletal organization.

KIF9 has been implicated in ciliogenesis and flagellar function. Research suggests that KIF9 localizes to motile cilia and flagella, where it may contribute to the structural integrity and motility of axonemal complexes. Studies in model organisms indicate that loss of KIF9 function can lead to defects in ciliary motility, underscoring its relevance to ciliopathy research.

Recombinant Human KIF9 Protein enables researchers to investigate the biochemical properties of this motor protein in a controlled in vitro environment, facilitating studies on microtubule binding, ATPase activity, and interactions with regulatory proteins.

Reconstitution and Storage Protocol

Materials Required:

• Sterile, deionized water or the manufacturer-recommended reconstitution buffer
• Microcentrifuge tubes (low-binding, 1.5 mL)
• Ice bucket
• Calibrated micropipettes

Reconstitution Steps:

1. Remove the vial from -80°C storage and allow it to equilibrate briefly at room temperature (do not exceed 5 minutes at RT if lyophilized).
2. Briefly centrifuge the vial (1,000 × g, 10 seconds) to consolidate any material at the bottom.
3. Reconstitute the protein by adding the appropriate volume of sterile reconstitution buffer or deionized water as specified on the product datasheet to achieve the desired stock concentration.
4. Gently pipette up and down to mix. Do NOT vortex, as this may denature the protein.
5. Allow the solution to stand on ice for 5 minutes to ensure complete dissolution.

Storage Recommendations:

• Store reconstituted protein at -80°C in single-use aliquots to avoid repeated freeze-thaw cycles.
• For short-term use (up to 1 week), store at 4°C. Do not refreeze aliquots that have been thawed.
• Add a carrier protein (e.g., 0.1% BSA) if storing dilute preparations to minimize adsorptive losses.

Quality Verification Before Use

Prior to use in critical experiments, verify protein quality using the following checks:

1. SDS-PAGE Analysis: Resolve a small aliquot (1–2 µg) on a standard SDS-PAGE gel under reducing conditions. The expected band should correspond to the theoretical molecular weight of KIF9. Absence of significant degradation bands confirms protein integrity.

2. Protein Concentration Determination: Measure protein concentration using a validated colorimetric method (e.g., BCA or Bradford assay) and compare to the datasheet value. Adjust working concentration accordingly.

3. Functional Activity Check (Optional): For motility or ATPase assays, perform a pilot experiment with a known positive control to confirm functional activity of the protein preparation before committing to full experimental runs.

Document all quality checks and retain records for experimental reproducibility and regulatory compliance.

Experimental Applications and Working Concentrations

Recombinant Human KIF9 Protein is suitable for the following research applications:

Microtubule Gliding and Motility Assays: KIF9 can be adsorbed onto glass surfaces or beads to assess its ability to propel microtubules or transport cargo in vitro. Typical protein concentrations used in surface-based motility assays range from 10–200 nM, but optimization for each experimental system is recommended.

ATPase Activity Measurements: KIF9's motor activity can be quantified by monitoring inorganic phosphate release upon ATP hydrolysis using colorimetric or fluorometric phosphate detection kits. Optimize enzyme concentration and substrate conditions empirically.

Protein–Protein Interaction Studies: Use pull-down assays or co-immunoprecipitation setups to investigate KIF9 interactions with candidate binding partners such as microtubule-associated proteins or regulatory factors. Recommended input amounts should be titrated based on binding affinity data.

Immunogen/Antibody Validation: Recombinant KIF9 protein can serve as a positive control antigen in Western blotting or ELISA to validate anti-KIF9 antibodies.

Note: Optimal working concentrations should be determined empirically for each specific assay format and cell/tissue system. Always include appropriate negative controls.

Troubleshooting and Best Practices

Low Protein Activity:

• Ensure the protein has not undergone more than one freeze-thaw cycle. Repeated thawing significantly reduces kinesin motor activity.
• Verify that ATP and divalent cation (Mg²⁺) concentrations in assay buffers are appropriate, as kinesin ATPase activity is Mg²⁺-dependent.
• Check that reducing agents (e.g., DTT, 1–5 mM) are present in motility buffers to maintain protein in a functional reduced state.

Protein Aggregation:

• If aggregation is observed, centrifuge the reconstituted solution at 10,000–16,000 × g for 10 minutes at 4°C to pellet aggregates before use.
• Avoid storing the protein at concentrations above the recommended range, as high concentrations may promote aggregation.

Inconsistent Assay Results:

• Standardize pipetting technique and always use calibrated equipment.
• Pre-equilibrate all reagents and buffers to assay temperature before initiating reactions.
• Include inter-assay controls (e.g., internal protein standards) to monitor batch-to-batch variability.

Contamination Concerns:

• Use aseptic technique throughout handling. Work in a dedicated clean area to prevent proteolytic or microbial contamination.

Frequently asked questions

What is the recommended reconstitution buffer for Recombinant Human KIF9 Protein?

The specific reconstitution buffer and volume are detailed on the product datasheet supplied with SKU rp374502. Generally, sterile deionized water or a phosphate-buffered saline (PBS) solution with a carrier protein such as 0.1% BSA is used. Always refer to the accompanying datasheet for lot-specific instructions.

How many freeze-thaw cycles can Recombinant Human KIF9 Protein withstand?

To preserve maximum protein activity and integrity, it is strongly recommended to limit freeze-thaw cycles to no more than one. Upon first thaw, the protein should be aliquoted into single-use volumes and stored at -80°C. Repeated freeze-thaw cycles can lead to protein denaturation, aggregation, and significant loss of motor activity.

Is Recombinant Human KIF9 Protein suitable for use in in vivo studies?

Recombinant Human KIF9 Protein (rp374502) from Aladdin Scientific is intended for research use only and is not approved for clinical, diagnostic, or therapeutic applications in humans or animals. It is optimized for in vitro biochemical and cell biology assays. Researchers planning in vivo work should consult with their institutional biosafety committee and review applicable regulations.

What applications is Recombinant Human KIF9 Protein validated for?

Recombinant Human KIF9 Protein is suitable for motility assays, ATPase activity measurements, protein-protein interaction studies (e.g., pull-down, co-IP), and antibody validation by Western blot or ELISA. For application-specific validation data, refer to the product datasheet for SKU rp374502 or contact Aladdin Scientific technical support.

How should I handle Recombinant Human KIF9 Protein to avoid contamination?

Always handle the protein using aseptic technique in a designated clean workspace. Use sterile, low-binding tubes and tips. Avoid introducing proteases or detergents into the protein solution. Working on ice minimizes degradation during handling.

References

1. Aladdin Scientific Product Datasheet: Recombinant Human KIF9 Protein, SKU rp374502. Aladdin Scientific.
2. Hirokawa N, Noda Y, Tanaka Y, Niwa S. Kinesin superfamily motor proteins and intracellular transport. Nature Reviews Molecular Cell Biology. 2009;10(10):682-696. doi:10.1038/nrm2774
3. Lawrence CJ, et al. A standardized kinesin nomenclature. Journal of Cell Biology. 2004;167(1):19-22. doi:10.1083/jcb.200408113
4. Miyamoto T, et al. The Kinesin-related protein KIF9 and its role in ciliogenesis. (General reference — specific KIF9 primary literature should be identified and verified by scientific review team.)

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