POSSIBLE ROLE OF SIGNALLING PEPTIDES IN MAMMALIAN PROTEIN EXPRESSION, IN SILICO

Abstract

Signal-peptides are found in proteins, and target proteins to different organelles in the cell. Proteins that are targeted to the endoplasmic reticulum (ER) are either retained in the lumen of the ER, or further transported to other cellular organelles. Specific targeting of proteins to inside the cell is defined by specific sequence motifs. The presence of signalpeptides in human proteins was investigated in silico to determine overall distribution of proteins in the cell. 1000 human proteins were retrieved from the UniprotKB database. Different bioinformatic tools were utilized to determine these proteins cellular localization. Highest number of proteins was found to be located in the ER (~85%) and around 15% were found in the golgi apparatus or the mitochondria, suggesting that proteins leaving the ER, are most likely to be directed to the golgi or mitochondria. Smaller number of proteins was also found in lysosomes, cytoplasm or membrane. Cellular compartmentalization into organelles is an important mechanism of the cell. Incorrect transport of proteins to intracellular compartment can lead to pathological conditions, as the protein does not reach its proper site, causing either inactivation or misregulation of important signalling cascades.