Phosvitin
Egg yolk phosphoprotein
From Wikipedia, the free encyclopedia
Phosvitin is one of the egg (commonly hen's egg) yolk[1][2] phosphoproteins known for being the most phosphorylated protein found in nature.[3][4][5] Phosvitin isolation was first described by Mecham and Olcott in the year 1949.[3][6] Recently[when?] it has been shown that phosvitin orchestrates nucleation and growth of biomimetic bone like apatite.[7]
Structure
As the most phosphorylated natural protein, phosvitin contains 123 phosphoserine residues accounting for 56.7% of its total 217 amino acid residues.[3][8] The structure of phosvitin at large consists of 4-12 base pair stretches of serines, interspersed with amino acid residues lysine (6.9%), histidine (6.0%), and arginine (5.1%), among others in smaller quantities.[9] Phosvitin's structure (right) is adapted from the protein vitellogenin (Gene: VTG2; Uniprot: P02845; residues 1-1850) generated by AlphaFold, where all the possible phosphorylated serine residues are highlighted in red. Phosvitin is one of four proteins cleaved from vitellogenin and is unstructured at neutral pH.[3] Despite phosvitin only accounting for 16% of total proteins in egg yolk, it alone accounts for 60% of the total yolk phosphoproteins as well as 90% of the total yolk phosphorus.[10][8]
Function
Due to phosvitin's polyanionic activity, the protein performs functionalities such as metal chelation, emulsification, and nutrition sequestration for a growing embryo.[3] Additionally, in recent[when?] research it has been shown that the disordered secondary structure of phosvitin orchestrates nucleation and growth of biomimetic bone like apatite.[7]
