How to search phosphorylation sites of a certain protein:
There are two ways, in order to search for phosphorylation sites of a certain protein:
On the one hand, you can search via gene symbol or protein name.
On the other hand, you can search via sequence (case-insensitive). It is possible to use the entire protein sequence, but also short parts of it (e.g., peptide sequences).

Examples: hasC, atpG, elongation factor G , ...