High impact information on YCK2

• It has been proposed that they are detected by a two-component system, because overexpression of the histidine kinase gene CKI1 induces typical cytokinin responses and genes for a set of response regulators of two-component systems can be induced by cytokinins [1].
• Akr1p, purified to near homogeneity from yeast membranes, catalyzes Yck2p palmitoylation in vitro, indicating that Akr1p is itself a PTase [2].
• We show that inactivation of a protein phosphatase 2A (PP2A) or overexpression of one of two kinases, Yck2p or Pkc1p, can specifically suppress the sphingoid base synthesis requirement for endocytosis [3].
• In Saccharomyces cerevisiae, the redundant YCK1 and YCK2 genes (Yeast Casein Kinase 1) are required for viability [4].
• Increased dosage of YCK1 suppressed defects caused by reduced SNF1 protein kinase activity, and increased dosage of YCK2 relieved sensitivity of wild-type cells to salt stress [5].

Biological context of YCK2

• Casein kinase I-like protein kinases encoded by YCK1 and YCK2 are required for yeast morphogenesis [6].
• An impairment in endocytosis was found for gcs1 delta mutant cells, which was alleviated by an increased YCK2 gene dosage [7].
• In yeast, the products of the redundant YCK1 and YCK2 genes are together essential for cell viability [8].
• Despite partial colocalization with the Yck proteins, Hrr25p is unable to rescue the yck1 delta yck2 delta phenotype [9].
• Yck1p and Yck2p are peripheral plasma membrane proteins, and we report here that the localization of Yck2p within the membrane is dynamic through the cell cycle [8].

Anatomical context of YCK2

• At cytokinesis, GFP-Yck2p becomes associated with a ring at the bud neck and then appears as a patch of fluorescence, apparently coincident with the dividing membranes [8].
• Furthermore, palmitoylation is sufficient for specific association of Yck2p with secretory vesicles destined for the plasma membrane [10].

Associations of YCK2 with chemical compounds

• Mutations in both YCK1 and YCK2 affect this regulation, suggesting that H+-ATPase activity is modulated by glucose via a combination of a "down-regulating" casein kinase I activity and another, yet uncharacterized, "up-regulating" kinase activity [11].
• Kinetic analysis demonstrates that YCK2 is similar to casein kinase-1 isolated from other organisms in its inability to use GTP as nucleotide substrate, in its sensitivity to heparin and ribofuranosyl-benzimidazole inhibitors, and in its peptide substrate selectivity [12].
• We previously described normal plasma membrane targeting of a Yck2p construct with the final five amino acids of Ras2p substituting for the final two Cys residues of Yck2p [10].
• Because Akr1p, the palmitoyl transferase for Yck2p, is located on Golgi membranes, it is likely that Yck2p first associates with Golgi membranes, and then is somehow recruited to budding plasma membrane-destined vesicles [10].
• The CKI1-encoded choline kinase (ATP:choline phosphotransferase, EC 2.7.1.32) from Saccharomyces cerevisiae was phosphorylated in vivo on multiple serine residues [13].

Other interactions of YCK2

• The subcellular distribution of three casein kinase I (CK1) homologs, encoded by the YCK1, YCK2, and HRR25 genes, has been determined in budding yeast through a combination of subcellular fractionation and immunofluorescence methods [9].
• The Yck2 yeast casein kinase 1 isoform shows cell cycle-specific localization to sites of polarized growth and is required for proper septin organization [8].
• Akr1p appears to function in localizing Yck1p-Yck2p to the plasma membrane, a localization that depends on prenylation of C-terminal dicysteinyl motifs [14].
• Mutations in the plasma membrane-bound casein kinase I isoforms, Yck1p and Yck2p, abolished Pdr5p phosphorylation and modified the multiple drug resistance profile [15].
• Loss of either Tlg2p or Rgp1p causes inefficient localization of Yck2p, suggesting that its transport may be directed, in part, by a targeting factor that must be recycled back to the Golgi [16].

Analytical, diagnostic and therapeutic context of YCK2

• A 22-kDa phosphorylatable protein, copurifying with YCK-2, can be removed by ultracentrifugation at low ionic strength and is shown by several criteria to be unrelated to the beta subunit of LCK-2 [17].

References