The electrophoretic mobilities of three commercially available standard phosphoproteins,
β-casein in the SuperSep Phos-tag precast gel system with
Tris–glycine (T–G), Tris–Tricine (T–T), or Tris–MOPS (T–M) as the electrophoretic running buffer.
The phosphoprotein migrated a shorter distance than did its completely dephosphorylated counterpart prepared by treating the phosphoprotein with alkaline phosphatase (AP) for 60 min. Partially dephosphorylated forms (AP 5-30 min) were observed as multiple bands. In the systems using Tris–Tricine and Tris–MOPS buffers, more phosphorylated species were detected than in the system in which Tris–glycine buffer was used. However, in the Tris–MOPS system, we found that the degree of migration of all bands was much smaller and that bands were relatively distorted.