CDK (Cyclin-dependent kinase) belong to CMGC family. CDKs are ser/thr protein kinases that play an important in regulation of a number of cellular processes in eukaryotes. CDKs are also characterized by its feature that they require an activation subunit called cyclin (1).

Reference
1. Casteel, D.E., Zhang, T., Zhuang, S. and Pilz, R.B. (2008) cGMP-dependent protein kinase anchoring by IRAG regulates its nuclear translocation and transcriptional activity. Cell Signal, 20, 1392-1399. PMID: 18450420

    CDKL (Cyclin-dependent kinase-like kinase) belong to CK1 family. Five members have been found in human genome. The function and regulation of these kinases remain to be studied (1).

Reference
1. Manning, G., Whyte, D.B., Martinez, R., Hunter, T. and Sudarsanam, S. (2002) The protein kinase complement of the human genome. Science, 298, 1912-1934. PMID: 12471243

    CK2 is found in all eukaryotes examined, usually in one or two copies (CK2a1 and CK2a2 in human, also known as CSNK2A1 and CSNK2A2. CK2 also has a beta (b) subunit, and usually forms a tetramer of either or both of the two catalytic subunits and two beta subunits (1).

Reference
1. Wikinome annotation:    Kinase Family CK2

    CLK kinases belong to CMGC family. CLKs are evolutionarily conserved dual specific kinase, which possess ability to mediate phosphorylation on serine, threonine and tyrosine residues. Four members have been found in human genome, known as CLK1, CLK2, CLK3 and CLK4. CLKs can be found in diverse species, including yeast, fly, Arabidoposis, mouse, rat and human. CLKs play an important role in cellular processes. The work on Drosophlia CLK homologue DOA reported that low expression of DOA show the neurologic abnormalities. In addition, more studies have identified the other physiological roles of CLK family of kinases, including regulation mRNA splicing; participate in intracellular signal transduction cascades (1).

Reference
1. Moeslein, F.M., Myers, M.P. and Landreth, G.E. (1999) The CLK family kinases, CLK1 and CLK2, phosphorylate and activate the tyrosine phosphatase, PTP-1B. J Biol Chem, 274, 26697-26704. PMID: 10480872

    DYRK (Dual-specificity tyrosine-regulated kinase) belong to CMGC family. Homology within the kinase domain can further classify this family into three subfamilies: DYRK kinases, homeodomain-interacting protein kinases (HIPKs), and pre-mRNA processing protein 4 kinases (PRP4s). Ten members have been found in human genome. DYRKs are characterized as dual-specificity protein kinases for their ability to mediate the phosphorylation of serine, threonine and tyrosine residues; however, the tyrosine phosphorylation activity is restricted to autophosphorylation. DYRKs play an important role and act as pleiotropic regulators in a variety of cellular functions, including cell survival, cell differentiation, gene transcription and endocytosis. Mutation or abnormal expressions always associate with diseases. Truncation mutants of DYRK1A result in clinical phenotypes, including microcephaly, intrauterine growth retardation, and developmental delay. Overexpression of DYRK1B has been reported in solid tumors, including colon and lung cancer, pancreatic ductal adenocarcinomas, and rhabdomyosarcomas, and experimental data suggest that increased amounts of DYRK1B favor tumor development (1).

Reference
1. Aranda, S., Laguna, A. and de la Luna, S. (2011) DYRK family of protein kinases: evolutionary relationships, biochemical properties, and functional roles. FASEB J, 25, 449-462. PMID: 21048044

    GSK (Glycogen synthase kinase 3) belong to CMGC family. Two isoforms have been identified in human genome, known as GSK3A and GSK3B. GSKs are highly conserved and have been found in nearly all eukaryote. Sequence analysis show that two genes display 85% sequence identity, and even higher in the catalytic domain (93%). Chromosomal mapping identified the cytological location of human GSK3A as 19q13.2, whereas human GSK3B maps to 3q13.3. Northern blot analysis shows that GSKs are expressed in different mammalian tissues. GSKs play an important role in a variety of cellular signaling pathways, including cellular proliferation, migration, inflammation and immue responses, glucose regulation and apoptosis (1).

Reference
3. Ali, A., Hoeflich, K.P. and Woodgett, J.R. (2001) Glycogen synthase kinase-3: properties, functions, and regulation. Chem Rev, 101, 2527-2540. PMID: 11749387

    MAPK (mitogen-activated protein kinase) are serine/threonine specific protein kinases belonging to CMGC kinase group. MAPKs play an important role in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflammatory cytokines. MAPKs are involved in regulation of a variety of cellular processes, including cell proliferation, gene expression, differentiation, mitosis, cell survival and cell apoptosis. Three subfamilys constitute MAPK family, extracellular-receptor kinases (ERK), the c-Jun N-terminal kinases/stress-activated protein kinases (JNK/SAPK) and p38 MAPKinases. MAPK signaling pathways are important in animals, fungi and plants. ERK1/2 pathway is best understood in animals, which is essential for cell proliferation and cell cycle. Fus3 pathway is also well studied in fungi, which is responsible for cell cycle and mating in responses to pheromone stimulation. MAPKs pathway in plants may response to osmotic shock, oxidative stress, cold and anti-pathogen responses (1).

Reference
1. Wikipedia Annotation:    Mitogen-activated protein kinase

    RCK family is composed of two subfamilies, known as MOK and MAK subfamily. MAK subfamily member MAK is essential for the regulation of ciliary length and required for the long-term survival of photoreceptors. MAK can mediate the phosphorylation of FZR1 in a cell cycle-dependent manner. Plays a role in the transcriptional coactivation of AR. Could play an important function in spermatogenesis. MAK may also play a role in chromosomal stability in prostate cancer cells. MOK family member is able to phosphorylate several exogenous substrates andto undergo autophosphorylation (1).

Reference
1. UniProt Annotation:     MAK_HUMAN

    SRPK (serine-arginine (SR) protein kinase) belong to CMGC family. Three members have been identified in human genome, which are known as SRPK1, SRPK2 and SRPK3. SRPKs are characterized by the ability to phosphorylate the serine residues located in regions rich in arginine/serine dipeptides, known as RS domains. More than 100 proteins contain RS domains, indicating that SRPKs are involved in a variety of cellular functions, including regulation and function in mRNA maturation, regulation of chromatin binding to the nuclear envelope, regulation of chromatin reorganization during G2/M phase progression, regulation of cyclin transcription and involved in metabolic signaling (1).

Reference
1. Giannakouros, T., Nikolakaki, E., Mylonis, I. and Georgatsou, E. (2011) Serine-arginine protein kinases: a small protein kinase family with a large cellular presence. FEBS J, 278, 570-586. PMID: 21205200