631190-9-47P AID: 2498 | 23/12/2015
The discrepancy between the number of genes and proteins is due to alternative splicing and posttranslational modifications. These two mechanisms facilitate the production of different proteins from the same gene. Alternative splicing particularly combines exons and excludes introns in different combinations. So, different mature mRNAs can be produced from the same transcribed mRNA. Post-translational modification refers to the covalent and generally enzymatic modification of proteins that take place before or after their synthesis. For example, proteins encoded by the same gene can be phosphorylated at different amino acids and performs different functions.