er Protein 169939-93-9 chemical information Kinases A, G, and C. In other organisms, this group includes cyclic nucleotide or phospholipidregulated kinases, G-protein coupled kinases, ribosomal protein S6 kinases, and related proteins. This represents 13% of the ePK kinome, which is the same fraction as observed in humans based on the annotation of Manning et al. and the number of genes in the current build of that genome, but less than in T. pseudonana and H. arabidopsidis. Since P. infestans and H. arabidopsidis are both oomycetes this difference is notable, and a later section of this paper focuses on other differences between their kinomes. The composition of each ePK subfamily in these two oomycetes is also compared in Judelson and Ah-Fong BMC Genomics 2010, 11:700 http://www.biomedcentral.com/1471-2164/11/700 Page 6 of 20 only one GPCR-regulated kinase was detected, PITG_16476. This low number of GRKs might be explained by the observation that some P. infestans GPCRs contain a phosphatidylinositol phosphate kinase domain which may be capable of protein phosphorylation. Members of the MAST, NDR, RSK and SGK subfamilies were also detected. While three AGC kinases had catalytic domains that appeared nearly equidistant between PKA and PKC, none bore the C1 or C2 ligand-binding domains typical of PKC in other taxa. PKC is also absent from Dictyostelium discoideum and plants but in metazoans and yeast, which is consistent with the suggestion that it arose late in evolution. The detection of cGMP-regulated ePKs in P. infestans is of particular interest. Their absence from plants, D. 
discoideum, and yeast led to a prior suggestion that PKG is metazoan-specific. Since our identification of the PKG proteins was based on the traditional approach of studying the ePK catalytic domain where differences between different AGC subfamilies are subtle, the possibility of misclassification was considered. However, all six predicted PKGs contain the expected cyclic nucleotide binding domains. We can also detect PKG in the sequenced genomes of ciliates such Paramecium tetraurelia, apicomplexans such as Toxoplasma gondii, and diatoms such PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19796622 as T. pseudonana. The shared occurrence of PKG in these species is not surprising since these groups and stramenopiles reside on the same branch of the eukaryotic tree, with the ciliates and apicomplexans closer to the root and the diatoms closer to the tip. Due to this taxonomic affinity, comparisons between oomycete, apicomplexan, and ciliate kinomes will be highlighted in many of the following sections of this paper. Two of the predicted PKG proteins, PITG_08304 and PITG_09375, did not cluster near the rest in CAMK family Seventy P. infestans ePKs are within this category, making it the second largest. For CAMK, the CAMK1 group clusters well with that human subfamily, but others could not be unambigously assigned and are instead placed into four oomycete-specific clades. For the TKL family, the MLK/LRRK subfamily combines MLK and LRRK-like kinases, since these were not clearly separated in phylogenetic analyses, and the same is true for the RIPK/STRK subfamily. The relative size of the CAMK family in P. infestans slightly exceeds that of metazoans, where Ca2+ is known to play major roles in cellular regulation. However, it is also demonstrated that Ca 2+ controls many stages of oomycete development. Nevertheless, less than 10% of P. infestans ePKs in the CAMK family bear accessory domains consistent with regulation by Ca2+. About half contain size
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