Cells express unique O-glycoproteomes. To visualize the O-glycoproteome of each cell, the presence or absence of individual glycosites was illustrated using unclustered heat maps. Glycosites were ordered alphabetically by Uniprot accession and subsequently by position in the protein. (A) Total O-glycosylation illustrating the overlap of unique, unambiguous glycosites identified in each sample. (B) Comparison of O-glycosite identification on key hemostatic factors between different sample types. (C) A detailed view of differential O-glycosylation of fibronectin across samples. Individual O-glycosites identified in fibronectin are plotted by sample type in order of position on the protein, with N-terminal sites plotted closest to the origin. Numbers indicate total glycosite count per protein. (D) Differential O-glycosylation of proteins in the hemostatic system. The hemostatic O-glycoproteome was filtered to identify proteins represented by >5 spectra in each sample and with similar spectral counts between samples (total protein spectral counts differing by <10) to ensure comparable O-glycosite coverage was achieved between samples. These proteins demonstrated both overlapping and also cell-specific glycosylation as exemplified in (D). Drawing is to scale; the arrowhead indicates the protein extends beyond illustration. Shading indicates number of sites per protein (A), protein identity (B), or sample type (C). a.a., amino acid.