this method has been developed for purification of two phosphoproteins ( mr 19,000 and 30,000 ) from 32pi-prelabeled , isoproterenol-stimulated rat parotid tissue and is based on the observation that , in the presence of urea and nonidet-p40 , ionic detergent-solubilized proteins can be adsorbed by ion exchangers according to their own charge .
C0031689
phosphoproteins
C0033684
proteins