Posttranslational Modifications of Proteins and Their Role in Biological Processes and Associated Diseases

A posttranslational modification (PTM) depicts an imperative means for diversification and regulation of the cellular proteome due to its tremendous scope in various biological processes such as replication, histone modifications, transcription, translation, cell signaling, apoptosis, and cancer, etc. Most PTMs occur in a time- and signal-dependent manner, and determine the overall structure of proteins and also their function in regulating various biological processes. Most PTMs are brought about by small molecular weight functional groups such as phosphate, acyl, acetyl, amide, alkyl, myristoyl, palmitoyl, prenyl, hydroxyl, ubiquitin, and sugars to the amino acid side chains of the protein. Advanced molecular techniques have enumerated more than 200 posttranslational modifications and, in fact, many of them have been discovered recently. Posttranslational modifications can take place at any stage during the maturation of the protein, whereas other modifications usually take place after the process of folding and sorting of proteins and are responsible for their catalytic activity. Study of posttranslational modifications and their mechanism of regulation of various cellular signaling pathways have significant medical implications. Identification, description, and mapping of the posttranslational modifications are very important for discerning their functional implications in a biological context. Therefore, an accurate understanding of protein posttranslational modifications is very important, not only for gaining insight about a multitude of cellular functions and associated diseases, but also regarding drug development for many life-threatening diseases such as neurodegenerative disorders and cancer. The present chapter will therefore attempt to summarize the role of PTMs in various important biological processes and also to provide future insights in this direction.