Non-protein phosphorylation has three general forms
* As a regulatory mechanism to control the function of the substrate, similar to the role of protein phosphorylation. Phosphoinositide lipids are important signaling molecules that have a variety of dedicated kinases and phosphatases.
* As an energetic intermediate. The phosphate bond is high-energy, so adding a phosphate increases the energy of a molecule, and removal of the phosphate can provide energy for an otherwise unfavorable reaction. For instance Glucose 6-phosphatase removes a phosphate group from glucose to complete gluconeogenesis.
* In biosynthesis, where the phosphate is a functional part of the mature molecule, and dephosphorylation degrades it or changes function. Nucleotidases are phosphatases used in nucleotide biosynthesis and breakdown.
The human non-protein phosphatome has been cataloged, but most phosphatome analyses are restricted to protein and lipid phosphatases that have regulatory functions.