List and characterize protein functions

Proteins have the following functions:
1. Catalytic. All biological catalysts – enzymes – are protein in nature.
2. Plastic (construction). Proteins are part of the cell membrane and form non-membrane cell structures (for example, the cytoskeleton) and part of the intercellular substance.
3. Transport. For example, hemoglobin carries oxygen in the blood; in the cell membranes there are special transport proteins that actively transfer certain substances into the cell.
4. Regulatory. Some hormones have a protein nature – insulin, pituitary hormones.
5. Signal. On the outer surface of the cell membrane there are many specific receptors of a glycoprotein nature that perceive external influences (hormones) or determine the nature of the interaction of the cell with the virus.
6. Propulsion. All types of movement are provided by specific contractile proteins (actin, myosin; microtubule proteins of the spindle division).
7. Protective. In response to the introduction of foreign substances (antigens) by blood cells (leukocytes), special proteins are synthesized – antibodies.
8. Energy. When splitting 1 g of protein, 17.6 kJ of energy (4.2 ical) is released.