Protein

Proteins are biological molecules which can have a very wide range of activities.

Role of proteins

Proteins carry a very wide range of functions within the cell or body.

They may play:

• a structural role (such as actin or tubulin contributing to the architecture of the cell, keratin which makes up hair ;
• an enzymatic role (such as DNA polymerase which recopies DNA) ;
• a hormonal role (such as insulin, which regulated blood glucose concentrations) ;
• a motor role (such as myosin, which transports molecules in the cell)…

Production of proteins

Proteins are coded for by genes and synthesised by ribosome during the process of RNA translation They are created by successive incorporation of amino acids, held together by peptide bonds in the order dictated by the succession of codons on the RNA.

Protein structure

Depending on their amino acid order and the binding between them, proteins take on particular conformations which are essential for them to function. Some structures are very commonly seen :

• the alpha helices, in which the amino acids form a helix through hydrogen bonds between each other;
• the beta sheets, where hydrogen bonds between the amino acids promote the formation of superimposed layers.

Post-translational chemical modifications can also contribute to their function (acetylations, phosphorylations, disulphide bridges...).