Proteins are of two types based on shape.
(i) Fibrous protein: The protein in which several polypeptide chains join together to form a fiber-like structure is called fibrous protein. They are insoluble in water because they contain hydrophobic amino acids. It provides mechanical and structural support to the organism. For example, fibrin, collagen, elastin, α-keratin etc.
(ii) Rounded protein: The protein which has round structure is called round protein. Most proteins in living organisms are globular proteins. Tertiary and quaternary structures are globular proteins. It is soluble in water, but insoluble in organic solvents. It provides mechanical and structural support to the organism. For example, myoglobin, hemoglobin, cytochrome-c etc.