Proteins are high-molecular organic substances that consist of alpha-amino acids that are connected by a peptide bond into a single chain. Their main function is regulatory. And about what and how it manifests itself, now it is necessary to tell in detail.
Process Description
Proteins have the ability to receive and transmit information. With this, their implementation of the regulation of the processes occurring in the cells and throughout the body as a whole is connected.
This action is reversible and usually requires the presence of a ligand. This, in turn, is the name of a chemical compound that forms a complex with biomolecules and subsequently produces certain effects (pharmacological, physiological or biochemical).
Interestingly, scientists regularly discover new regulatory proteins. It is assumed that only a small part of them is known today.
Proteins that perform a regulatory function are divided into varieties. And each of them is worth talking about separately.
Functionalclassification
She's pretty conventional. After all, one hormone can perform a variety of tasks. But in general, the regulatory function ensures the movement of the cell through its cycle, further transcription, translation, splicing and the activity of other protein compounds.
It all happens due to binding to other molecules or due to enzymatic action. By the way, these substances play a very important role. After all, enzymes, being complex molecules, accelerate chemical reactions in a living organism. And some of them inhibit the activity of other proteins.
Now you can move on to the study of species classification.
Proteins-hormones
They affect various physiological processes and directly on metabolism. Protein hormones are formed in the endocrine glands, after which they are carried by the blood in order to transmit an information signal.
They spread randomly. However, they act exclusively on those cells that have specific receptor proteins. Only hormones can contact them.
As a rule, slow processes are regulated by hormones. These include the development of the body and the growth of individual tissues. But even here there are exceptions.
This is adrenaline - a derivative of amino acids, the main hormone of the adrenal medulla. Its release provokes the action of a nerve impulse. The heart rate increases, blood pressure rises, and other responses occur. It also affects the liver - it provokes the breakdown of glycogen. As a result, glucose is released into the blood, and the brainwith muscles use it as a source of energy.
Receptor proteins
They also have a regulatory function. The human body is, in fact, a complex system that constantly receives signals from the external and internal environment. This principle is also observed in the work of its constituent cells.
So, for example, membrane receptor proteins transmit a signal from the surface of a structural elementary unit inwards, simultaneously transforming it. They regulate cellular functions by binding to a ligand located on a receptor on the outside of the cell. What happens in the end? Another protein inside the cell is activated.
It is worth noting one important nuance. The vast majority of hormones affect the cell only if there is a specific receptor on its membrane. It may be a glycoprotein or another protein.
One can give an example - β2-adrenergic receptor. It is located on the membrane of liver cells. If stress occurs, then the adrenaline molecule binds to it, as a result of which the β2-adrenergic receptor is activated. What happens next? The already activated receptor activates the G-protein, which further attaches GTP. After many intermediate steps, glycogen phosphorolysis occurs.
What is the conclusion? The receptor performed the first signaling action that led to the breakdown of glycogen. It turns out that without it, the subsequent reactions occurring inside the cell would not have occurred.
Transcriptional regulator proteins
One moretopic that needs to be addressed. In biology, there is the concept of a transcription factor. This is the name of proteins that also have a regulatory function. It consists in controlling the process of mRNA synthesis on a DNA template. This is called transcription - the transfer of genetic information.
What can be said about this factor? The protein performs a regulatory function either independently or in conjunction with other elements. The result is a decrease or increase in the binding constant of RNA polymerase to regulated gene sequences.
Transcription factors have a defining feature - the presence of one or more DNA domains that interact with specific DNA regions. This is important to know. After all, other proteins that are also involved in the regulation of gene expression lack DNA domains. This means that they cannot be classified as transcription factors.
Protein kinases
When talking about what elements perform a regulatory function in cells, it is necessary to pay attention to these substances. Protein kinases are enzymes that modify other proteins by phosphorylation of amino acid residues with hydroxyl groups in the composition (these are tyrosine, threonine and serine).
What is this process? Phosphorylation usually changes or modifies the function of the substrate. The activity of the enzyme, by the way, can also change, as well as the position of the protein in the cell itself. Interesting fact! It is estimated that about 30% of proteins canbe modified by protein kinases.
And their chemical activity can be traced in the cleavage of the phosphate group from ATP and further covalent attachment to the rest of any amino acid. Thus, protein kinases have a strong influence on cellular vital activity. If their work is disrupted, various pathologies can develop, even some types of cancer.
Protein phosphatase
Continuing to study the features and examples of regulatory function, we should pay attention to these proteins. The action carried out by protein phosphatases is the elimination of phosphate groups.
What does this mean? In simple terms, these elements perform dephosphorylation, a process that is the reverse of that which occurs as a result of the action of protein kinases.
Regulation of splicing
You can't ignore her either. Splicing is a process in which certain nucleotide sequences are removed from RNA molecules, and then the sequences that are preserved in the "mature" molecule are joined.
How does it relate to the topic being studied? Within eukaryotic genes, there are regions that do not code for amino acids. They are called introns. First, they are transcribed into pre-mRNA during transcription, after which a special enzyme cuts them out.
Only those proteins that are enzymatically active participate in splicing. Only they are able to give the desired conformation to prem-RNA.
By the way, there is still the concept of alternative splicing. It's very interestingprocess. The proteins involved in it prevent the excision of some introns, but at the same time contribute to the removal of others.
Carbohydrate metabolism
Regulatory function in the body is performed by many organs, systems and tissues. But, since we are talking about proteins, then the role of carbohydrates, which are also important organic compounds, is also worth talking about.
This is a very detailed topic. Carbohydrate metabolism as a whole is a huge number of enzymatic reactions. And one of the possibilities of its regulation is the transformation of enzyme activity. It is achieved due to the functioning molecules of a particular enzyme. Or as a result of the biosynthesis of new ones.
It can be said that the regulatory function of carbohydrates is based on the feedback principle. First, an excess of the substrate that enters the cell provokes the synthesis of new enzyme molecules, and then their biosynthesis is inhibited (after all, this is precisely what the accumulation of metabolic products leads to).
Regulation of fat metabolism
A last word about this. Since it was about proteins and carbohydrates, then fats should also be mentioned.
The process of their metabolism is closely related to carbohydrate metabolism. If the concentration of glucose in the blood rises, then the breakdown of triglycerides (fats) decreases, as a result of which their synthesis is activated. Reducing its quantity, on the contrary, has an inhibitory effect. As a result, the breakdown of fats is enhanced and accelerated.
From all this follows a simple and logical conclusion. The relationship between carbohydrate andfat metabolism is aimed at only one thing - to meet the energy needs experienced by the body.
