The secretome is the set of proteins expressed by an organism and secreted into the extracellular space.
The term secretome was coined by Tjalsma and colleagues in 2004 to denote all the factors secreted by a cell, along with the secretory pathway constituents.
[5][6] The secreted proteins in humans account for 13–20% of the entire proteome and include growth factors, chemokines, cytokines, adhesion molecules, proteases and shed receptors.
[2] Human protein-coding genes (39%, 19613 genes[7]) are predicted to have either a signal peptide and/or at least one transmembrane region suggesting active transport of the corresponding protein out of the cell (secretion) or location in one of the numerous membrane systems in the cell.
Increasing evidence showed that, in addition to the protein cargo, non-protein components, such as lipid, micro-RNAs and messenger-RNA, could also be secreted by cells via both microvesicles (100–>1000 nm diameter) − shedding from the plasma membrane − and exosomes (30–150 nm diameter) − released via endosomal-exocytosis event.