1. It can be used regardless of the type and position of amino acid residues.
   Able to analyze unknown phosphoproteins.
   Able to detect new phosphorylation sites for which anti-phospho antibodies are not commercially available.
2. Phosphorylated forms with different number and location of phosphorylated sites can be separated.
   Able to determine the level of phosphorylation and the number of phosphorylated forms.
3. It can be used to detect phosphorylated and non-phosphorylated forms simultaneously.
   Able to quantify each phosphorylated form.
   Able to determine the presence of phosphorylation easily.
4. Radioisotopes and special equipment are not needed.
   Experiments can be carried out easily at low costs (Only SDS-PAGE reagents and equipment are required).
5. After electrophoresis, WB- and MS-based analyses and 2D gel electrophoresis can be performed.
   WB: Internal proteins can be analyzed.
   MS: The combinations of phosphorylated sites for each phosphorylated form can be determined.
   2D gel electrophoresis: Phosphorylated forms with identical isoelectric points or molecular weights can be separated.

Application: Time Course of α-casein Dephosphorylation
Phos-tag^™ SDS-PAGE and conventional SDS-PAGE were performed to separate samples of α-casein, which had been dephosphorylated over time (incubation period: 0-120 mins) by alkaline phosphatase.