FIGURE 3.

Phosphopeptide mapping and affinity purification of Kv1.2-WT and T46A phosphopeptides and pSASTISK co-migrates with tryptic phosphopeptide derived from PKA-phosphorylated Kv1.2-WT. A, phosphopeptide maps of Kv1.2-WT-myc (a) and -T46A-myc (b) phosphorylated by cPKA in the presence of [γ-³²P]ATP. Data are representative of six independent experiments. + indicates the origin. B, radioactivity profile of PKA-phosphorylated Kv1.2-WT-myc tryptic peptides separated by immobilized metal affinity chromatography. C, pSASTISK was mixed with the tryptic digest of ³²P-phosphorylated Kv1.2-WT-myc and separated by electrophoresis and chromatography. Synthetic phosphopeptide (left) and ³²P-labeled phosphopeptides (right) were visualized by ninhydrin staining and autoradiography, respectively. + indicates the origin.