November 26, 2022 duration: 6 min

Recombinant protein: Definition, Examples & Production

Richard Park

Richard Park

Global Head, Client Relations and Business Development at evitria

Recombinant proteins are proteins that are artificially produced by introducing specific genes into host organisms, like bacteria or yeast. These genes instruct the host organisms to manufacture a particular protein, allowing for controlled and scalable production of proteins with various applications, including in medicine, research, and industry.

Recombinant protein plays an essential role in several scientific disciplines; correspondingly, recombinant protein expression has become one of the major techniques to produce highly desired protein products for biotechnology, life-science and academic research.

We will talk about recombinant proteins (recombinant DNA) and how high yields are generated by recombinant protein expression in manipulated cells in large-scale, for example for the production of recombinant antibodies. You will receive an overview of the processes involved in the biological flow of information from genetic code to the finalized recombinant protein.

We also reveal examples of recombinant proteins. But first, there is a definition of recombinant protein.

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Recombinant protein: Definition

Recombinant proteins are expressed from a recombinant DNA template, using molecular biology techniques.

The necessary recombinant DNA is generated by the artificial combination of genetic material from different sources, which would not occur in nature. Recombinant DNA technology allows the engineering and optimization of genes to code for artificial, optimized proteins and includes measures to facilitate higher yields.

The recombinant genes are then subjected to amplification and inserted into host cells, where they are used as blueprints for cellular protein expression.

Recombinant proteins are products of high interest in biotechnology, medicine and the life-sciences.

Types of recombinant proteins

There are several types of recombinant proteins, each with distinctive fields of application. Frequent recombinant protein types in a clinical setting are:

  • interferons
  • recombinant hormones
  • tumor necrosis factors
  • interleukins
  • thrombolytic drugs
  • blood clotting factors​1​

All of these recombinant protein types have allowed to open new medical possibilities in the treatment of countless patients.

Recombinant protein examples

Examples for recombinant proteins are

  • human insulin: treatment against diabetes
  • human growth factors: treatment for growth hormone deficiency
  • factor VIII: treatment for hemophilia
  • therapeutic monoclonal antibodies, e.g. as treatment for cancer or viral infections such as SARS-COV-2
  • various research reagents for e.g. ELISA and fluorescence assays, inhibitors, receptors for small molecules, protein folding and many more

Prior to the rise of molecular biology and high-throughput recombinant protein technology, these proteins had to be harvested from animal sources.

In addition, fully artificial recombinant proteins became available, such as protein fragments for vaccine production, recombinant antibodies for therapeutic and diagnostic applications and associated labeling with additional residues to simplify characterization and chromatography (e.g. GST).

Benefits of recombinant proteins

Recombinant proteins bring a huge set of benefits to the life sciences and healthcare sector, being used in western blotting, ELISA testing and other techniques.

Major benefits of recombinant proteins are:

  • High Purity: Recombinant proteins can be produced with a high degree of purity, reducing the risk of contamination or impurities in experimental applications.
  • Customization: Researchers can design and produce recombinant proteins with specific modifications, tags, or mutations to suit their experimental needs.
  • Scalability: The possibility to scale up recombinant protein production makes it suitable for industrial and therapeutic applications.
  • Consistency: The production of recombinant proteins can be tightly controlled, ensuring consistent quality and reproducibility in experiments or drug manufacturing.
  • Cost-Effectiveness: Compared to traditional methods of obtaining proteins from natural sources, recombinant protein production can be more cost-effective, especially for rare or complex proteins.

Due to their manifold advantages, recombinant proteins are widely used tools all over the scientific landscape. For instance, researchers can design a recombinant protein as an antibody, being able to bind to one specific target antigen in the body. This makes them unique weapons in the fight against several cancer types as well as other medical conditions.

Issues with recombinantly produced proteins

The production of recombinant proteins is challenging and bound to several risks and issues. Not only does this process require an enormous amount of resources and know-how, but failures in the manufacturing or underscoring regulatory standards can have severe consequences for patients as well as financial drawbacks.

Issues in recombinant protein production may include

  • proteolysis
  • incorrect folding
  • formation of inclusion bodies
  • protein aggregation​2​

Especially for therapeutic proteins, stringent quality control is indispensable to measure the biological activity, stability and other factors related to the quality and effectiveness of recombinant proteins.

Recombinant protein production

Recombinant protein production, also referred to as recombinant protein expression, is defined by the Encyclopedic Reference of Genomics and Proteomics in Molecular Medicine​3​ as the method of inserting a recombinantly manipulated gene into a suitable vector and its transfer into suitable cells, depending on the protein type.

Subsequently, the cells are grown in culture to a high concentration and, after proliferation, harvested to yield the recombinant protein.

In general, protein expression is the biological process of protein production in cells. The first step is the transcription of a DNA blueprint into messenger RNA (mRNA). Messenger RNA is the template for a cell’s protein production machinery, the so called ribosome.

Ribosomes read the code in messenger RNAs and then assemble peptides and proteins sequentially from individual amino acids.

Recombinant protein expression uses artificial genetic material that is optimized by molecular biology. This engineering process also involves genetic signals in expression vectors to enhance yields (promoters). Molecular cloning methods enable scientists to combine genetic material across different species, e. g. human insulin in yeast cells.

Next, recombinant DNAs are manipulated for introduction into host cells, usually by generation of circular DNAs (plasmids) or by packaging them into viral particles. These vectors are then inserted into the host cells by processes termed transformation and transfection.

When the DNA blueprints arrive in the interior of a host cell, its own biological machinery takes over to do the remaining protein production work according to the blueprint.

How are proteins changed to recombinant proteins?

Recombinant protein expression - evitria

Transcription & Translation

First, enzymes in the cell read the DNA sequences and rewrite it into RNA. This is the process of transcription. These enzymes read the genetic code and assemble RNA strands that contain the sequence of the desired protein with high specificity to minimize mutations. Reverse transcription, which transcribes RNA into DNA (cDNA) is another important biochemical technique.

A computer analogy is to view DNA as biological long-term data storage and RNA as short term working memory with executable instructions.

Next, ribosomes are recruited and attach to the RNA strands. They read the information encoded in the RNA and attach amino acids selectively in the right sequence to produce the full-length protein.

The finished protein is released from the ribosome, which in turn attaches to the next RNA strand. The released protein then may undergo further cellular processing steps, refolding into the proper 3D shape and post-translational modifications.

Recombinant protein expression systems

Recombinant protein expression systems refer to some types of host cells that have proven superior for several protein synthesis needs:

  • mammalian: for recombinant antibody production and highly complex proteins
  • bacterial: for simple proteins, but is scalable at low cost; simple culture conditions
  • yeast: advanced protein processing, intermediate culture conditions
  • insect cells: similar to mammalian protein processing, demanding culture conditions and time consuming

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Recombinant protein expression with mammalian systems

Recombinant protein expression with mammalian systems yields synthetic target proteins that are made up very much like their native counterparts. The reason is the very similar biochemistry production machinery, leading to similar post-translational modifications like glycosylation that closely match in vivo patterns.

Recombinant human proteins from mammalian systems therefore show very high physiological functionality and are preferred for recombinant antibody production and protein tools for functional assays and research, whereas in vitro gene expression in simpler microorganisms such as Escherichia coli (E. coli) can’t provide the same high-quality proteins of interest.

Mammalian expression systems allow stable expression after insertion of recombinant genes into the host cell line genome.

More practically relevant is transient protein expression and protein purification of recombinant proteins in suspension mammalian cell culture (1-2 weeks). One of the usual host cell type for the manufacture of recombinant proteins is HEK293, although transient expression of a protein of interest in CHO cells is the superior method and yields titers of up to several grams per liter.

Citations:

  1. 1.
    Recombinant Proteins. Science Direct. Accessed October 2023. https://www.sciencedirect.com/topics/neuroscience/recombinant-protein
  2. 2.
    Beygmoradi A, Homaei A, Hemmati R, Fernandes P. Recombinant protein expression: Challenges in production and folding related matters. International Journal of Biological Macromolecules. Published online April 2023:123407. doi:10.1016/j.ijbiomac.2023.123407
  3. 3.
    Langlais C, Korn B. Recombinant Protein Expression in Bacteria. In: Encyclopedic Reference of Genomics and Proteomics in Molecular Medicine. Springer Berlin Heidelberg; :1609-1616. doi:10.1007/3-540-29623-9_4800

Frequently asked questions

A recombinant protein is a protein that has been produced by the means of recombinant DNA – DNA that has been modified in order to encode the blueprint of a protein of interest. Recombinant proteins are produced in host cells, in which recombinant DNA has previously been inserted so that the cells’ ribosomes are instructed to express the recombinant protein instead of what the cells’ original DNA would have encoded.

Recombinant protein examples are

  • human insulin
  • human growth factors
  • factor VIII – treatment for hemophilia
  • therapeutic monoclonal antibodies
  • various research reagents

Recombinant proteins are widely used in many fields of life sciences, e.g. for research purposes, but also in the treatment of various diseases. This is because they are frequently chosen in the production of biopharmaceuticals, for instance when designing monoclonal antibody therapies. In the treatment of diabetes, recombinant proteins are also an essential keystone, being used in the production of human insulin. Read more about the use of recombinant antibodies.

In biotechnology, recombinant proteins are proteins that have been produced by host cells, according to artificially modified DNA (recombinant DNA) instead of the cells’ own DNA. The recombinant DNA is inserted into host cells by the means of a suitable vector, after which protein expression commences according to this blueprint.

Once harvested, recombinant proteins are used for various purposes within life sciences and medicine, e.g. in research, but also in the treatment of several diseases.

Recombinant describes biologic material that has been produced by genetic modification/recombination. DNA is modified in order to encode a desired protein, which is then expressed by host cells. Read more: What is recombinant?

Yes, human insulin consists of recombinant proteins; in fact, human insulin was the first drug that has been made with the means of recombinant DNA to be licensed.

Recombinant DNA is DNA that, by the means of laboratory techniques, was modified in order to generate new genomic sequences that would otherwise not occur in nature, combining genetic material from different sources. Recombinant DNA, for instance, allows the engineering of recombinant proteins.

Read more on: What is recombinant DNA?

Recombinant antibodies are primarily produced in eukaryotic cells, such as mammalian cells or yeast, due to their ability to perform complex post-translational modifications necessary for antibody functionality.

The price for recombinant proteins can vary, depending on factors like the specific protein type, as well as the required quantity and quality. Additionally, the desired expression system plays a role in determining the price of recombinant protein production.

Recombinant protein production techniques include:

  • genetic engineering, DNA cloning and vector design
  • transfection of host cells (bacterial, yeast, mammalian)
  • protein expression and purification
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