The protein structural properties, such as accessible surface area (ASA) and secondary structure, can be considered in the future to improve the predictive performance of the models. For instance, ASA may be used for reducing the number of false-positive predictions of phosphorylation sites which locate in buried regions. However, the number of experimental phosphorylation sites located in the protein regions with known structure from PDB (22) is few for each kinase-specific group. Although ASA and secondary structure can be predicted by several published tools such as RVP-net (23) and PSIPRED (24), respectively, the predictive performance of phosphorylation sites may be affected by the predictive structural properties.
