Identification of INAD Phosphorylation Sites.

A, Representative Coomassie-stained polyacrylamide gel of protein extracts from wild type fly heads that were immunoprecipitated with an α-INAD antibody. The INAD band at ca. 75 kDa was excised, digested with trypsin, and subjected to nanoLC-ESI mass spectrometry. MS/MS spectra of identified phosphopeptides are shown in S2 B Fig., Cartoon of the INAD protein structure showing the positions of PDZ domains (modified from [7]) and the identified phosphorylation sites. C, INAD amino acid sequence depicting peptides that were identified by mass spectrometry (85.9% sequence coverage, highlighted in yellow) and identified phosphorylation sites indicated by red letters.