Table S1.

Calculated abundances of peptides representing variously digested forms of the Ser66 and Ser458 loci of DET1

Peptides from the Ser66 locus were analyzed by a standard LC-MS/MS method, and those from the Ser458 site were analyzed by a targeted method specially tailored to favor hydrophobic, later-eluting features. An unmodified Det1 peptide (FFQYFDQLR) with characteristics amenable to both methods was quantified in each as a measure of consistency. Rows representing phosphorylated peptides are shaded pink. Values reported for the percent of phosphorylation were made in a locus-specific manner as Det1_phos/Det1_total. For the Ser66 locus, Det1_total is the summed abundance of all four peptides quantified from this locus, including the two unmodified species (FSPDGR, KFSPDGR) and the two pSer66 phosphopeptides (FsPDGR, KFsPDGR; the lowercase “s” denotes the phosphorylated residue). Det1_phos is the summed abundance of the two pSer66 phosphopeptides. At the Ser458 locus, Det1t_otal is the summed abundance of the four peptides measured from this locus, i.e., the unmodified and phosphorylated versions RLLGQLPISAQSYSGSPYLDLSLFSYDDK, LLGQLPISAQSYSGSPYLDLSLFSYDDK and RLLGQLPISAQSYSGsPYLDLSLFSYDDK, LLGQLPISAQSYSGsPYLDLSLFSYDDK. Italicized sequences correspond to phosphorylated peptides.