Both serine/threonine and tyrosine protein kinases share a catalytic core with the protein kinase (IPR011009). A nucleotide binding site and catalytic apparatus are found in the interlobular cleft of the catalytic domain. Phosphate groups are chemically added to some proteins to alter them. PK_Ty_Ser-Thr, or IPR001245, is a serine-threonine kinase. Both serine/threonine and tyrosine protein kinases contain catalytic domains.Atypical protein kinases include RIO kinase (IPR000687) is compared to other ePKs like serine/threonine kinases or insulin receptor tyrosine kinases, the conformation of ATP bound to RIO kinase is different, suggesting that the catalytic aspartate of RIO kinases is involved in phosphate transfer. This mechanism may operate differently than the well-studied serine/threonine ePK. The N-terminal domain of the HPR serine/threonine kinase PtsK is represented by the HPr Serine kinase N terminus (Hpr kinase N, PF02603). Carbon catabolic repression in bacteria is regulated by a multicomponent phospho-relay system, of which this kinase serves as the sensor. The EH domain (IPR000261) is commonly linked to membrane transport and the regulation of protein transport and sorting. There is evidence that the EH domain binds to specific peptides through hydrophobic interactions. However, its affinity for short, unmodified motifs is low. Native MEME was used to compare the downloaded sequences associated with Mg+serine-threonine kinase and insects to the Chinese wheat mosaic virus coat protein. As shown in Table , the protein kinase domain of the coat protein is found near the N-and C-termini. The Chinese wheat mosaic virus coat protein has eight protein kinase motifs. The protein kinase C motif contains the Mg2+ site at position A243. At its core, the coat protein contains two overlapping PK_Tyr_Ser-Thr domain motifs with the protein kinase domain. Ala243, the Mg2+ site, is near PK_Tyr_Ser-Thr A. Since Thr is absent from PK_Tyr_Ser-Thr, coat protein is considered a serine protein kinase. As shown in Table , the Mg2+ binding site is located in the RIO kinase B and Hpr kinase NB regions, as shown in Table . As is the case with all serine-protein kinases, when Mg2+-ATP binds to Ala243, the serine-threonine kinase activity of coat protein is turned on. Ca(2+)/CaM-dependent autophosphorylation, substrate phosphorylation, and CaM binding are common features of serine/threonine protein kinases. Ca2+ binding to the EF-Hand of coat protein and Mg2+ binding to A243 activates serine protein kinase activity. Coat protein loses its serine protein kinase activity once PK_Tyr_Ser-Thr is autophosphorylated.