What is protein expression? Protein expression happens when a gene found in an organism ends up expressed by another organism, allowing the new organism to express proteins that are not normally expressed. It is the process in which scientists make proteins, naturally developed in living cells, outside of living cells.
To put it simply, scientists take genes from living cells and put them into other cells or organisms to make desired proteins for specific purposes like diagnosis, disease treatment, and research.
Understanding the process of protein expression
The process of protein expression begins with the isolation of the gene encoding the desired protein. This specific gene is isolated from a known source or by producing it artificially, followed by putting it inside the cell in which you want to make that particular protein. From here, scientists can make millions of identical copies of the chosen proteins. Then the proteins produced are purified and tested in the laboratory. However, there are several methods by which protein expression can be accomplished, but this piece will focus on prokaryotic expression and eukaryotic expression.
Prokaryotes are organisms whose cells lack a membrane-bound nucleus. It’s within these cells that protein production takes place, which is why prokaryotic cells are the most used in the biosynthesis of proteins for biomedical research. Prokaryotic expression, therefore, refers to the process where the genetic code of a gene is transferred to a prokaryotic cell, leading to its transcription and translation, followed by the synthesis of the desired protein.
Transcription is initiated when RNA polymerase binds to promoter sequences upstream (5′) from the transcription start site (3′). These sequences can be a part of a gene or can simply be a segment within the genome. Then, RNA polymerase cleaves the RNA at specific sites to initiate transcription and falls off after it has synthesized an RNA strand long enough to code for the required protein.
In translation, messenger RNA (mRNA) copies the genetic code from the gene, through a process of base pairing. In prokaryotes, translation is carried out on ribosomes found in the cytosol. The mRNA searches for a ribosome and attaches itself to it via its own Shine-Dalgarno sequence (ribosome binding site). Then it moves closer to the Shine-Dalgarno sequence of the next mRNA, where it will attach. On the ribosome are three binding sites for tRNA containing amino acids, anticodons complementary to the mRNA codon at one end, and a special ester linkage that attaches to an adjacent site on either tRNA or mRNA at the other end.
Protein expression is extremely useful because if we can control what cells make and how they make it, we can use them for specific purposes. Let’s look at some ways that protein expression has become useful.
It can be used in pharmaceuticals for therapeutic drugs
Protein expression is used in a variety of fields including pharmaceuticals, biochemistry, and the food industry. In the pharmaceutical industry, protein expression allows for the isolation of pure proteins from living cells that can be used as therapeutic drugs to combat diseases or health issues. In the food industry, it’s used as a stabilizing agent, which makes it useful for many different food products.
For instance, Trichoderma reesei is used to produce recombinant protein for pharmaceutical applications because it has been shown to have the ability to process ‘difficult’ substrates such as hydrophobic peptides. There’s more to it though, if you desire, you can learn more about t reesei as a type of protein expression system. However, in addition, it allows for the isolation of pure proteins from living cells that can be used as therapeutic drugs to combat diseases or health issues.
Disease treatment and diagnosis
This can be improved through protein expression. When a gene found in an organism is transferred to another organism, the gene would end up expressing proteins that are not normally expressed by its parent organism. Assuming that said new organism doesn’t have any genetic diseases of its own, then the offspring will end up healthier than before. This is because the new organism is expressing proteins that fight diseases. If a child has inherited genetic disorders and there is no way to fix said disorder, then protein expression can be used to work around the problem.
This would basically mean that some parts of the old mutated gene will be cut away and substituted by genes with healthy code, allowing for protein expression to happen without compromising the host’s original genetic code.
Examples of disease treatment and diagnosis through protein expression include:
– α 1 -antitrypsin deficiency
– cystic fibrosis
– Duchenne muscular dystrophy
– sickle cell anemia
– hemophilia A and B
Biomedical research to understand health and disease
In the field of biomedicine, it is often necessary to have a certain protein or enzyme activity under study. In order to do so, one needs purified and isolated proteins for testing, as well as a system in which the function of those proteins can be studied. In many cases, if not almost always, these proteins need to be produced in large quantities for later use. This is where protein expression comes into play, the production of proteins in sufficient quantity to be used in biomedical research and possible therapeutic treatments.
Basic life science research
Protein expression is a complex biological process in which a specific gene is expressed and then translated into how that protein will look and behave. Bioscience researchers use this system to both understand the function of proteins and to study them directly for drug development processes. There are several methods of studying these proteins, but one of the most common is through the use of expressed proteins.
Expression can occur in a variety of ways, but there are basically three different types. The first, called prokaryotic expression, involves the use of certain bacteria that have been engineered to produce foreign proteins under normal operations. The second is similar but uses different strains of bacteria. Since they are not harmful to humans, these lab-scale bacteria are often the primary source of proteins used in research. The third, called eukaryotic expression, involves the use of yeast to produce large quantities of proteins that are then purified into a usable form for injection or other purposes.
Study the protein behaviors in cells and organisms
Protein expression allows scientists to study the structure, function, and interactions of proteins, which is important to all biological processes. This is a method for studying proteins, which are important structural molecules that carry out many tasks within our cells. Proteins are an important part of most biological processes, so it is crucial to be able to study them.
Studying the protein behaviors in cells and organisms can offer scientists key information about how proteins work, which helps them to find out why they do the things that they do.
Protein expression is the process by which cells synthesize proteins that are encoded in DNA. They play a role in virtually all biological processes, including DNA replication. Proteins are necessary for life, and they often serve as molecular machines, each with its own specific role in cellular functions. Protein expression systems are common in biomedical research, allowing scientists to better understand human diseases so that they may come up with cures or treatments for those afflictions.