Fig. 3.

Predicting phosphorylation/O-GlcNAcylation crosstalk. (A) Motif for crosstalk with phosphorylation on P−3 and O-GlcNAc on 0. (B) The frequency of all four amino-acid combinations in the human proteome. The sequences matching the predicted crosstalk motif are in red. (C) The number of occurrences of each sequence from the crosstalk motif (red bars) compared with the number expected if this sequence were to occur at random (gray bars), taking into account that some amino acids are more abundant in the human proteome. The sequences that are also deposited in the PhosphoSitePlus database, i.e., those containing phosphorylation residues within or immediately surrounding the motif, are shown in orange. (D) O-GlcNAc incorporation after 24 h on nine bioinformatically predicted OGT substrates (Table 1) with and without phosphorylation at P−3.