Page 112 - The Miracle of Protein

110 THE MIRACLE OF PROTEIN

The system works as follows: Ubiquitin is a small protein
made up of 76 amino acids. Its duty is finding and tagging
damaged, degraded or expired proteins. A protein with this tag

attached to it means that it has to be destroyed. Tagged pro-
teins are taken to a molecule called ‘proteasome’, which is an-
other miracle structure. Proteasomes cut the proteins into
smaller pieces and neither the parts obtained as a result of this
cutting, nor the remaining amino acid chains are wasted. They

are recycled for re-use. In this way, undamaged amino acids
will be used again. In other words, there exists not only a qual-
ity control system, but a very effective recycling system as well.
Three scientists won the Nobel Prize for chemistry in 2004, for

discovering this incredible mechanism. 38

Damaged proteins are tagged by ubiquitin and cut out of the amino acid
chains by another protein called proteasome.