Proteins are the workhorses of our cells. They perform most functions, from transporting molecules across membranes to enabling cells to communicate with each other—genes code for the amino acids that make up these proteins through transcription. We rely on proteins so much that having adequate amounts available is essential, so ensuring the availability of the amino acids that make up these proteins is critical.
Here’s what you should know about protein and genes:
Some Proteins Are Not Made Directly From Genes
There are some cases where a protein is not made directly from genes—for example, in making the proteins that produce energy within cells. Instead, these proteins are created from other proteins that have been coded for by genes and then synthesized into larger units called peptides. Also, one of the protein expression systems is Pichia Pastoris which uses yeast to make proteins that are expressed initially in the cytoplasm and then inserted into membranes. Difficulties arise when proteins are too large to fit through the membrane. They should be secreted out of the cell, but some strategies have been developed to deal with this problem.
Proteins Are Made From Amino Acids
Many people don’t understand that proteins are made from amino acids, which are coded for by genes. You can think of a gene as a blueprint—specific sequences of DNA code tell an organism’s machinery how to make particular kinds of proteins. DNA strands are composed of four nucleotide molecules called adenine, cytosine, guanine, and thymine (abbreviated A, C, G, T). The sequence of these molecules determines what order the amino acids will appear in a protein. Amino acids come together like puzzle pieces to form a protein. For example, the genetic code for leucine is CTN; without going into too much detail about how this all works, this means that there are three “pieces” of leucine (the “CTN”) that fit together to make one leucine protein.
There Are 5 Protein Expression Systems
The primary ways organisms make proteins are by transcription, translation, the UTR sequence, mRNA editing, and alternative splicing. Transcription is how a gene is read to form an RNA copy of that gene. By “copying” the DNA code into RNA code, cells can create templates for specific kinds of proteins rather than have to rely on using whatever amino acids are around at any given time—a process called translation. The RNA copy produced by transcription serves as a template for creating proteins during “translation” when amino acids are brought together to develop specific proteins based on the order of nucleotides in the RNA code.
Protein Expression Can Be Used To Study Proteins
Although it’s sometimes said that you can’t study individual atoms, the opposite is true. For example, if you wanted to learn the shape of a specific protein, one method would be to crystallize it and then shoot X-rays at it to get high-resolution 3-D images of its structure. Depending on how much force you used when shooting these beams of light at the protein crystals, slower-moving or stationary molecules might produce different results—in other words. Their position will change ever so slightly depending on how hard X-rays hit them. This gives us clues as to what types of forces must be acting upon these proteins within cells. These methods also study the structures of other kinds of molecules, such as DNA.
Insulin Is A Protein Hormone
Insulin is a protein hormone produced by the pancreas. It tells cells to take up glucose from the bloodstream throughout the body, which lowers blood glucose levels. The cells that insulin targets are called “glucose sensors” or “glucose transporters”—they sense changes in glucose levels and tell the pancreas to produce insulin whenever they detect low blood sugar. Insulin has many cellular effects—one of its most important jobs is telling fat cells to take up unused energy to be converted into an energy storage molecule called glycogen.
Protein Expression has numerous Benefits
Much like yellow Diavolo tomatoes have higher concentrations of “sun gold” carotenoids than other similar varieties, there are certain benefits to producing specific types of proteins in yeast versus expressing them through more traditional means. Here are a few examples:
Enzymes Work Better in Yeast Cells
When you produce enzymes outside of their typical environment, they often lose functionality. For example, taking an enzyme that breaks down lactose and places it in your mouth will not function the same way as when it’s in a cell. However, you can keep the yeast alive outside of their normal cellular environment by giving them a rich broth of sugars and amino acids to eat with plenty of oxygen (just like if they were in the wild). This is why products such as lactase enzymes are often dissolved in sugar syrups—the enzyme does not work efficiently if it has been taken out of its original context.
Prevent Reactions When Using Recombinant DNA
When we introduce foreign DNA into an organism, we can sometimes get undesired results. The most common example is the production of antibodies to these foreign proteins, but this can also happen even without immune system involvement. For example, if we take a gene that encodes for insulin or cellulase and places it into maize or cress, these plants will start to produce large quantities of the proteins encoded by those genes. However, suppose our DNA is slightly different from what would occur naturally. In that case, this can trigger an immune response in humans—this is why scientists are cautious about using recombinant DNA technology without thorough testing.
Protein Expression is Safer Than Traditional Animal Expression
People want proteins produced in yeast cells rather than animal cells because yeast-produced proteins are much less likely to be recognized as foreign molecules. This means that they are less likely to induce immune responses or allergies. For example, many vaccines rely on surface antigens to trigger immune responses; these are proteins found outside certain types of cells. Since yeast produces these same surface antigens, they can be used to create vaccines that are much safer for people with allergies or immune system disorders because there’s a smaller chance that your body will react negatively.
Protein expression in yeast cells is a vital tool scientists use to produce proteins of interest. The benefits are vast and broad-reaching, from simple model vaccines to difficult-to-obtain enzymes for breaking down cellulosic biomass.
