Proteins play a fundamental role in nearly all biological processes. Due to their diversity they can assume many different configurations and they can play varied roles in cells and tissues.
Some protein functions are noteworthy: the structural function (cell membrane proteins, cytoskeleton proteins, proteins of the connective tissue), the enzymatic function (enzymes are proteins), the energy storage function (proteins can be degraded into acetyl-CoA and “cycle” the Krebs cycle), the osmotic regulation function (albumin), the transportation function (membrane channels, respiratory pigments), the immune protection function (antibodies), the movement function (contractile proteins), the endocrine integration function (hormones) and the informative function (membrane receptors, intracellular signalers). There are also many proteins whose biological functions are not yet known.
