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Phosphorylation Sites

Phosphorylation sites are crucial for proteins and their transportation and functions. They are the covalent modification of proteins through reversible phosphorylation. This enables proteins to stay inbound within a cell since the negative phosphorylated site disallows their permeability through the cellular membrane. Protein dephosphorylation allows the cell to replenish phosphates through release of pyrophosphates which saves ATP use in the cell. An example of phosphorylating enzyme is found in E.Coli bacteria. It possesses Alkaline Phosphatase in its periplasmic region of its membrane. The outermost membrane is permeable to phosphorylated molecules however the inner cytoplasmic membrane is impermeable due to large negative charges. In this way, the E.Coli bacteria stores proteins and pyrophosphates in its periplasmic membrane until either are needed within the cell. Recent advancement in phosphoproteomic identification has resulted in the discoveries of countless phosphorylation sites in proteins. This required an integrative medium for accessible data in which known phosphorylation sites of proteins are organized. The work done by Shahid Ullah, Shaofeng Lin and team developed a curated database of dbPAF, containing known phosphorylation sites in H. Sapiens, M. musculus, R. norvegicus, D. melanogaster, C. elegans, S. pombe and S. cerevisiae. Their database currently holds 294,370 non-redundant phosphorylation sites of 40,432 proteins.