1. They are helpful in eliminating foreign substances and protect from infections. Antibodies are this type of proteins.
2. The proteins which act as a catalyst or facilitate biochemical reactions are enzymes. Eg. Pepsin a digestive enzyme useful to digest proteins in food.
3. Proteins that are involved in muscle contraction and movement are called contractile proteins. Eg. Actin, myosin.
4. Proteins which provide support to the body and serving as structural proteins, such as proteins present in connective tissues, are known as structural proteins. Eg. Collagen.
