A recombinant protein is any protein made from recombinant deoxyribonucleic acid (DNA). DNA holds all of an organism's genetic information and relays this information through protein expression. Recombinant DNA is a type of DNA that has been manipulated to include the DNA of another organism. When the new DNA is transcribed and translated to make a protein, a recombinant protein is the result.
Proteins are building blocks of life. Any trait seen on a human — such as hair color, eye color and even height — is determined by protein production. Many body functions are also the result of protein production. This includes insulin production and functioning of the immune system. Genetic defects in humans can sometimes be treated by creating recombinant proteins in a lab that can treat those conditions.
When the host of the recombinant DNA is an organism that reproduces quickly, such as bacteria, mass quantities of the recombinant protein can be produced. This technique, called amplification, is used extensively in cloning and gene therapy processes. Other hosts include yeast, fungi and even mammalian cells. The type of host necessary depends on the intended uses and amount of recombinant protein needed.
After the host is chosen, a vector can be decided. A vector is a vehicle that is used to insert the targeted DNA into the host DNA. Vectors are generally a modified version of a virus or a bacteria.
Some vectors are specially designed pieces of DNA attached to a non-coding region. These types of vectors are generally used for fusion proteins. Fusion proteins are made by pieces of DNA that are not normally connected. They are placed into the same vector for easier transfection.
All vectors have one or more different tags on them. These tags are used for recognition during a purification step in the recombinant protein production process. When a solution containing vectors is poured over a special column, the tags stick to the column in different places and can be separated from other parts of the DNA. This ensures that the correct DNA and vectors are inserted into the host.
After transfection of the host, it can then divide and begin producing the desired recombinant protein. These host cells can be cultured in a laboratory setting, and the protein can be collected as it is produced. These proteins are then purified for use in humans or other mammals. Bacterial hosts often do not produce all parts of the human protein. These proteins can be modified in the lab after purification.