Actin: Example of Contractile Protein
Introduction (classification criteria)
Proteins can be classified according to the functions they perform in the body.
They are those that act in transporting molecules into and out of cells. They are plasma membrane proteins.
Hemoglobin, for example, is a carrier protein. Present in red blood cells, it transports oxygen from the lungs to body tissues.
There are some types of hormones that are protein and have the function of regulating metabolic activities in the body.
We can cite as an example of insulin regulatory protein. Synthesized in the pancreas, it acts on lipid and protein metabolism, as well as being responsible for the entry of glucose into cells.
Defense Proteins (Antibodies)
They act on our body's immune system, that is, they have the function of protecting it from foreign organisms (viruses, bacteria, etc.) that penetrate our body.
Thrombin and fibrinogen are also defense proteins because they act on blood clotting in case of injuries and cuts, preventing blood loss.
These proteins have the function of accelerating and facilitating chemical reactions that occur inside the cells. Enzymes, for example, are catalyst proteins.
They are those that have the function of promoting the structural support to the body tissues. Examples include: elastin (acts on the structure of the skin) and keratin (acts on the structure of hair, nails and hair).
These proteins have the function of enabling the contraction of muscle fibers. Myosin and actin are examples of contractile proteins.