Proteins are the building blocks of life. These amino acids create our bones and muscles, replace old cells that die off, help us grow taller and stronger, cure disease, digest food…the list goes on.

It’s amazing how these 20 different amino acids (out of a total possible 20) can be put together to make so many diverse things. In this blog post we’ll explore the history of protein expression in order to better understand its future potentials. We’ll also look at some examples of where protein expression is used today for various purposes such as medicine or agriculture. We hope you enjoy this exploration into proteins.

Explaining protein expression

We all know what proteins are but do we really know how they work? What does it mean when they’re expressed? What’s the difference between a protein and a peptide? What is the structure of a protein? Let’s begin by taking a look at where proteins come from and how they’re expressed.

Proteins are made up of amino acids, which in turn are created from other smaller molecules like hydrogen, oxygen, and carbon. These small molecules are called precursors, meaning that they can be used to make a bigger molecule. Proteins are synthesized in living things through an enzymatic process that requires the protein to be expressed. Expression is the term used to describe this replication of proteins from their genetic codes. It’s all about using the information stored in DNA to make proteins.

What is DNA?

DNA (Deoxyribonucleic Acid) is made up of two chains of nucleotides called a helix, and each chain is also a strand. The strands are complementary copies that run opposite ways so that each one can fit into the other like a zipper. The 4 different nucleotides (adenine, thymine, guanine, cytosine) each have their own molecular structure with hydrogen bonds and form the building blocks of this amazing molecule called DNA that is so important to life.

DNA contains all the information needed for creating all types of proteins. But how does it do this? 

DNA’s double helix structure forms the basis of how our genetic code and all protein works. Basically, we all have two copies of a bunch of genes that are lined up alongside each other on our DNA strands to make one long chain (which is then separated into 23 pairs in the cell). 

Everything from hair color to blood type is coded into these pairs of genes, and different versions are passed on from parent to child. You inherit the copies of any given gene from your parents (one copy from each) which gives you total control over what your DNA looks like. If this wasn’t true then we wouldn’t get to choose our hair color or blood type.

When it comes to proteins, the different nucleotides on our DNA have three states they can be in. These are called triplets because each one refers to a specific amino acid (the building blocks of proteins). So let’s say that there are two genes, one named GGC and the other AAT. The first gene has two possible triplets: GGC and GGA. The second gene has two possible triplets as well, AAT and ATA. 

At this point you might be thinking ‘okay that’s all fine but how is this relevant?’ Well, let me explain. You may have noticed that the second gene has two triplets but there are three nucleotides in total, meaning AAT is a redundant combination of two other possible combinations – for example, can you spot the difference between ATA and AAT?

This redundancy is what allows for alternative forms of proteins to exist. The combinations of three nucleotides can be read in pairs, for example GTT = Valine + Thymine and CTT = Leucine + Cysteine. You may have also noticed that GGA looks just like GTA, which is a pair of another combination: Glycine + Arginine. So when the DNA strand is copied and made into RNA, the triplets can be read in different ways too.

The whole point of my explanation above is to show how DNA works and why protein expression occurs. Now I can reveal how proteins are expressed and created in living organisms. This amazing process starts with transcribing the genetic code from DNA into an intermediary molecule called messenger RNA or mRNA (don’t worry, you don’t need to remember this). This contains the information needed to create a protein molecule.

Messenger RNA is then taken through an enzymatic process to create the final product: a protein. The mRNA brings nitrogen, carbon dioxide, oxygen and hydrogen that can be used to form different types of proteins depending on what amino acids are available. 

Practical uses of protein expression

This process is used in a huge number of new opportunities and of applications, particularly in drug development. For example, genetic diseases that lead to protein dysfunction can be mitigated by the creation of synthetic proteins that are essentially better copies of those defective proteins.

Taking this further, you could have synthetic antibodies that act like human antibodies. These are usually produced by a recombinant protein production service which specializes in biological solutions. These ‘pharmaceuticals’ can be derived from natural sources but are more useful than using antibodies obtained from human blood as they last much longer and can be used for different purposes. This all sounds very sci-fi, but these applications are now going into production.

Synthetic proteins have huge implications in the medical field as they can increase our understanding of genetics and disease, and also lead to the development of cures.

Why is this important?

Protein expression has a huge impact on our understanding of genetics, disease treatment and how we test for traits. Without this process there would be no synthetic antibodies or natural proteins and creating drugs from living organisms would be impossible (at least until we found another way!). 

There are many benefits to understanding how protein expression and development work. The science behind these biological processes is fascinating, but the practical applications of this knowledge can be even more so. We hope that you’ve found some new information here today to help you better understand your own body.