Table 1. A summary of four human phospho-protein datasets in PhosphoPOINT.
PhosphoPOINT has integrated three existing phospho-protein databases, including Phospho.ELM, HPRD, SwissProt, and our manually curated 400 kinase-substrate pairs from the literature. Integration of these four datasets results in a collection of 4,195 phospho-proteins with 15,738 phosphorylation sites, consisting of 10,937 serine (S), 2,425 threonine (T), 2,376 tyrosine (Y) residues. Among these phosphorylation sites, 7,843 (6152+995+696) are from high-throughput (HTP) screening, 6,329 (3828+1152+1349) are from low-throughput analysis, and only 679 are both from HTP and LTP screening. One special note is that there are 887 phosphorylation sites, which do not have annotation from literature in the SwissProt database and it is not possible distinguish whether these are from HTP or LTP.
Figure 2. Distribution of interacting phosphoproteins for ten Kinase
518 kinases have been classified to ten kinase groups. The numbers of interacting phosphoproteins for ten kinase groups are illustrated. The X-axis is ten kinase groups and Y-axis is the number of phosphoproteins.
Figure 3. Detection of possible phosphoaccepter sites from 293 Known Kinase/Phosphatase Substrate/Binding Motifs.
A large number of motifs mapped to 1~250 phosphorylation sites. What merits attention is that, 91 Substrate/Binding motifs which probably come from in vitro experiment such as oriented peptide library approach mapped to zero phosphopeptides and three motifs mapped to greater than 4,000 ones.
Figure 4. cSNPs result in amino acids changes near phosphorylation sites (-7~+7).
Coding Single Nucleotide Polymorphism (cSNP) is a DNA sequence variation occurring when a single nucleotide differs between members of a species and causes the residues changed at protein sequences. To address whether the collected phosphorylation sites may exhibit any alterations, we have gathered cSNPs information from NCBI dbSNP. In addition to many cSNPs occur near the phosphorylation sites.