QUANTIFICATION OF SUBNANOMOLAR AMOUNTS OF PHOSPHATE BOUND TO SERYL AND THREONYL RESIDUES IN PHOSPHOPROTEINS USING ALKALINE-HYDROLYSIS AND MALACHITE GREEN

An assay for protein-bound phosphate with a capacity to determine 100 pmol of phosphate is described. It is based on the combination two well known methods: the alkaline hydrolysis of phosphate from seryl and threonyl residues in phosphoproteins and the quantification of the released phosphate by the use of malachite green and phosphomolybdate. © 1993 Academic Press, Inc.