Staining of alkali-labile phosphoproteins and alkaline phosphatases on polyacrylamide gels

A sensitive staining method for alkali-labile phosphoproteins has been developed. As little as 0.2 nmol bound P/mm2 can be detected. The procedure is based on alkaline hydrolysis, phosphate capture, and formation of an insoluble rhodamine B-phosphomolybdate complex. A further modification for the qualitative detection of alkaline phosphatase activity on polyacrylamide gels is proposed. During incubation, the released Pi is precipitated as lead phosphate and subsequently stained with rhodamine B.