An attempt to find changes of post-translational modifications on serum proteins between embryonic 15.5 fetuses and newborn rats

Blood is one of the most complex body fluids and plays important functions such as metabolic nutrient transport, signal conduction and immuno-modulatory. Proteins, the most important component of plasma, are considered the main executors of the physiological function of blood [1]. Posttranslational modifications (PTMs) of proteins can regulate protein functions by changing the physicochemical properties [2]. For example, phosphorylation or dephosphorylation may turn the kinase cascades in signaling on or off [3], and is often associated with tumorigenesis. So far, more than 500 types of PTMs or biological and chemical modifications have been identified and documented in the PSI-MOD [4], RESID [5], UniProt [6] and UniMod [7] databases. These translational modifications may determine the diversity of protein functions [8]. Research on post-translational modifications of plasma proteins with different physiological states could help to better understand and evaluate the function of plasma.