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Recombinant Protein Definition and Information |
What is a recombinant protein?
A recombinant protein is a manufactured protein that has been produced using cells engineered to carry a gene of interest. Recombinant proteins can have the same amino acid sequence as the corresponding naturally occurring (wild-type) protein, or have their sequence modified for improved properties such as solubility or production yield.
What are recombinant proteins used for?
There are myriad applications for recombinants proteins in biomedical research, as well as diagnostics and therapeutics. Recombinant proteins have become an important tool in various areas of science. Laboratory uses for recombinant proteins include:
- Cell culture supplements, including growth factors for primary cell expansion, differentiation, or stem cell reprogramming
- Generation of organoids and other 3D cell cultures for disease modeling and drug discovery
- Expansion of CAR-T cells by stimulation with recombinant cytokines
- Investigational tools for probing cellular function and cell signaling pathways
- Antigens for immunization and production of antibodies
- Components of functional cell-based assays such as cell migration and angiogenesis
Biologically active recombinant proteins
The above applications require that the recombinant protein be biologically active; that is, the protein is recognized by cells and cause changes in those cells. Bioactivity can be measured in an appropriate cell-based assay and quantified as a specific activity or EC50.
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Non-bioactive recombinant proteins may be used as standards in protein analysis studies including immunoassays such as western blotting, ELISA, gel shift, and immunohistochemistry.
Types of recombinant proteins
Many biologically important classes of recombinant proteins are available commercially, obviating the need to express, purify, and validate commonly used bioactive recombinant protein(s).
Major types of recombinant proteins include:
- Growth factors: a group of intercellular signaling proteins that cells produce and use to communicate. They stimulate a variety of cellular processes including cell division, differentiation, migration and survival. Prominent growth factor families include:
- FGF: fibroblast growth factors
- VEGF: vascular endothelial growth factors
- Neurotrophins: a subset of growth factors that act primarily on cells involved in the brain and nervous system
- Cytokines: including interferons, interleukins, pro-inflammatory cytokines, and chemokines critical to immune cell function and communication
- Enzymes: bioactive proteins that can perform chemical transformations; includes recombinant proteases, kinases, and nucleases
Learn more about chemokine structure and function
Explore cytokine and growth factor pathways
Recombinant protein manufacturing categories
When choosing a recombinant protein for a specific application, it helps to know which levels of quality control and documentation are required.
Research use only (RUO)
Research-grade recombinant proteins are suitable for a wide variety of life science research applications including development of cell models, maintaining cell phenotypes, and in vitro assays.
Animal-free
As an additional safeguard against animal pathogen contamination, animal-free recombinant proteins are made using raw materials that are not of animal origin.
GMP recombinant proteins
GMP-manufactured recombinant proteins undergo extensive testing and are accompanied by documentation to support projects/applications that require this level of rigor.
FAQs about recombinant proteins
Bioassays are intended to measure the biological activity of a given growth factor or cytokine. In most of the cases, the bioassays are cell-based tests using different indicator cells such as primary cells or cell lines. Commonly used bioassays include cell proliferation assay, chemotaxis assay, cytokine production assay, and cytotoxicity assay. The biological activity of a given cytokine is expressed as ED50, which represents the concentration of the cytokine that induces 50% of the maximum response.
The specific activity of a biologically active protein can be determined using the following equation:
1 x 106 / ED50 (ng/mL) = specific activity (units/mg)
The ED50 (AKA EC50) can be found on the CoA for the recombinant protein, but we advise determining the ED50 of a given recombinant protein in your functional assay system.
For additional information on ED50 and its relationship with specific activity, please refer to our Tech Tip.
First, centrifuge the container to concentrate the powder at the bottom of the tube. In general, we recommend reconstitution to a concentration of 0.1 to 1.0 mg/mL. Most proteins can be reconstituted with the addition of sterile, distilled water. However, the product data sheet or CoA will indicate when a diluent other than water is required. Recommended solutions, carrier protein concentrations and extended storage conditions can also be found on these documents.
In general, we recommend that lyophilized recombinant proteins be stored at –20°C, but short-term storage at 4°C or room temperature is permissible. For reconstituted protein solutions, we recommend that you make working aliquots containing at least 10 μL of protein solution and store at –20°C to –80°C. Do not allow multiple freeze-thaw cycles. Product-specific instructions for storage of lyophilized and reconstituted recombinant proteins are provided on either the product manual, data sheet, or certificate of analysis (CoA).
Recombinant proteins are usually formulated without carrier proteins or additives (e.g., BSA, HSA, sucrose, etc.). As a result, during lyophilization the protein product may be deposited on the vial as a thin, and sometimes invisible, film instead of a pellet. The size of the pellet, if any, is not directly related to the quantity of the recombinant protein in the vial.
To ensure complete recovery of protein product, before opening a vial of lyophilized recombinant protein, we recommend centrifuging it for 20–30 seconds to drive any protein that may be lodged in the cap or on the side to the bottom of the vial. After reconstitution, you can confirm the presence of product protein by running a small amount on SDS-PAGE. In general, a protein band with expected size should be visible with as little as 10 ng of protein loaded on an acrylamide gel.
Learn more about recombinant proteins and their applications
General
3D cell culture
Immunology
Neurobiology
Stem cells
Resources
Recombinant proteins learning center
Learn what recombinant proteins are, what they are used for, and what types are available
About PeproTech proteins
Learn about the PeproTech brand of recombinant proteins
Gibco cell culture basics
Learn about all aspects of cell culture
3D cell culture protocols
See which recombinant proteins are used to generate organoids
Western transfer protocols and recipes
Procedures and buffers for performing western blots
Cytokine and growth factor signaling pathways
Explore the role of proteins and cytokines in various signaling pathways
Support
Recombinant Proteins Support Center
Find Getting Started guides, protocols, troubleshooting, and other resources
Recombinant proteins FAQs
Search the database to find answers to your questions
Contact general support
Get technical or customer support for any recombinant protein; find SDS, CoA, and phone numbers based on a specific product
Contact GMP support
Get in touch with GMP technical and regulatory experts
Related Products
Intended use of the products mentioned on this page vary. For specific intended use statements please refer to the product label.
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