What negative (unphosphorylated) and positive (phosphorylated) control proteins do you recommend for use with the PhosphoProtein Purification Kit?
FAQ ID -779

We have used HSP-60 as a negative control with the PhosphoProtein Purification Kit because it is one of the very few proteins in eukaryotic cells that are always unphosphorylated. Alternatively, delipidated (i.e. phospholipid-free) BSA can be used.

Casein, which is completely phosphorylated, can be used as a positive control. Alternatively, Ovalbumin, which is not completely phosphorylated, may be used. It should bind at around 40-70%.