proteins are used for many structural functions such as in the acting and myosin in muscle or as a part of the cytoskeleton scaffolding that maintains cell shape. what other main function do proteins serve?

There are different types of proteins present which are made of amino acid sub-units. Proteins play various important functions in an organism's body. Some of these functions are:

Growth and maintenance of cells and individuals. Antibodies are proteins which provide immunity. Enzymes are proteins which catalyze different reactions. Many proteins allow movement of substances inside and outside of the cell membrane. They are known as carrier proteins. Many proteins serve as structural proteins.