Transport Role
Proteins transport biologically important compounds in the body. In some cases, the transported compound is sorbed by a protein molecule. This protects against destruction and ensures transport with the bloodstream (for example, albumin transport of some hormones, vitamins, medicinal compounds). This type of transport is called passive. In other cases, passive transport is combined with the deposition (storage) of certain compounds (for example, blood plasma transferrin transports not only iron but also stores (accumulates) it in excess). With the help of membrane proteins, compounds are transferred from zones of low concentration to a zone of high concentration (Boston University, 2016). This is associated with noticeable energy consumption and is called active transport (for example, transport of sodium ions from the cytoplasm and potassium to the cytoplasm).
Protective Role
The protective function of proteins is realized by antibodies, interferons, and fibrinogen. Antibodies are compounds of a protein nature, the synthesis of which is induced in the course of the immune response – the body’s response to the penetration of foreign proteins or other antigenic components into the internal environment (for example, high molecular weight carbohydrates). Antibodies, when combined with antigen, form an insoluble complex, making the antigen safe for the body (Walle, 2018). Interferons are glycoproteins synthesized by a cell after a virus enters it. Unlike antibodies, interferons do not interact with the antigen but cause the formation of intracellular enzymes. They block the synthesis of viral proteins, preventing the copying of viral information. This stops the virus from multiplying. Fibrinogen is a soluble plasma protein that, at the last stage of the blood coagulation process, is transformed into fibrin, an insoluble protein. Fibrin forms a skeleton of a thrombus that limits blood loss.
References
Boston University. (2016). Functions of proteins. Web.
Walle, G. (2018). 9 important functions of protein in your body. Healthline. Web.