Found in bones, muscles, skin, and tendons, collagen is the most abundant protein in the body.

The extracellular space in tissues contains an intricate network composed of two major classes of macromolecules: the glycosaminoglycan-protein assemblages known as proteoglycans and fibrous proteins including collagen as well as elastin, fibronectin and laminin.

Collagen is the most abundant protein in the human body, making up approximately one third of the body's protein content. The structure and synthesis of collagen are important in first semester biochemistry, and, as such, this material needs to get a share of attention for the new MCAT. The transformation of tropocollagen into collagen and the mechanism of hydroxylation of lysine and proline residues are subjects which are especially easy to envision as MCAT passages.