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Gene Review

PTK2  -  Ptk2p

Saccharomyces cerevisiae S288c

Synonyms: J1725, STK2, Serine/threonine-protein kinase PTK2/STK2, YJR059W
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High impact information on PTK2

  • Ptk2 has the strongest effect on Pma1, and ptk2 mutants exhibit a pleiotropic phenotype of tolerance to toxic cations, including sodium, lithium, manganese, tetramethylammonium, hygromycin B, and norspermidine [1].
  • Accordingly, ptk2 mutants exhibited reduced uptake of lithium and methylammonium [1].
  • A plausible interpretation is that ptk2 mutants have a decreased membrane potential and that diverse cation transporters are voltage dependent [1].
  • These results indicate that the putative STK2 Ser/Thr kinase gene is an essential determinant of high-affinity polyamine transport in yeast whereas its close homolog STK1 mostly affects a lower-affinity, low-capacity polyamine transport activity [2].
  • A 304-amino-acid stretch comprising 11 of the 12 catalytic subdomains of Stk2p is approximately 83% homologous to the putative Pot1p/Kkt8p (Stk1p) protein kinase, a recently described activator of low-affinity spermine uptake in yeast [2].

Biological context of PTK2


Anatomical context of PTK2

  • Among these latter mutants, three were deleted for genes involved in plasma membrane transport, including the L-carnitine transporter Agp2, as well as the kinases Ptk2 and Sky1, which are involved in regulating polyamine transport [5].

Associations of PTK2 with chemical compounds

  • We have isolated a new gene (PTK2) which restores spermine uptake of a polyamine uptake-deficient mutant of Saccharomyces cerevisiae (Kakinuma, Y., Maruyama, T., Nozaki, T., Wada, Y., Oshumi, Y., and Igarashi, K., 1995, Biochem, Biophys. Res. Commun. 216, 985-992) [3].
  • Transformation of stk2::lacZ cells with the STK2 gene cloned into a single-copy expression vector restored spermidine transport to wild-type levels [2].
  • In this study we find that Ptk2 localized to the plasma membrane in a Triton X-100 insoluble fraction [6].
  • Furthermore, we show that the Ptk2 carboxyl terminus is essential for glucose-dependent Pma1 activation and for the phosphorylation of Ser899 [6].

Enzymatic interactions of PTK2


Other interactions of PTK2

  • Two yeast kinases, SKY1 and PTK2, have been demonstrated to regulate polyamine tolerance [7].
  • Exogenous polyamine deprivation also derepressed residual spermidine transport in stk2::lacZ mutants, but simultaneous disruption of STK1 and STK2 virtually abolished high-affinity spermidine transport under both repressed and derepressed conditions [2].


  1. Regulation of yeast H(+)-ATPase by protein kinases belonging to a family dedicated to activation of plasma membrane transporters. Goossens, A., de La Fuente, N., Forment, J., Serrano, R., Portillo, F. Mol. Cell. Biol. (2000) [Pubmed]
  2. The STK2 gene, which encodes a putative Ser/Thr protein kinase, is required for high-affinity spermidine transport in Saccharomyces cerevisiae. Kaouass, M., Audette, M., Ramotar, D., Verma, S., De Montigny, D., Gamache, I., Torossian, K., Poulin, R. Mol. Cell. Biol. (1997) [Pubmed]
  3. A second gene encoding a putative serine/threonine protein kinase which enhances spermine uptake in Saccharomyces cerevisiae. Nozaki, T., Nishimura, K., Michael, A.J., Maruyama, T., Kakinuma, Y., Igarashi, K. Biochem. Biophys. Res. Commun. (1996) [Pubmed]
  4. Deletions of SKY1 or PTK2 in the Saccharomyces cerevisiae trk1Deltatrk2Delta mutant cells exert dual effect on ion homeostasis. Erez, O., Kahana, C. Biochem. Biophys. Res. Commun. (2002) [Pubmed]
  5. A genome-wide screen in Saccharomyces cerevisiae reveals altered transport as a mechanism of resistance to the anticancer drug bleomycin. Aouida, M., Pagé, N., Leduc, A., Peter, M., Ramotar, D. Cancer Res. (2004) [Pubmed]
  6. Yeast protein kinase Ptk2 localizes at the plasma membrane and phosphorylates in vitro the C-terminal peptide of the H+-ATPase. Eraso, P., Mazón, M.J., Portillo, F. Biochim. Biophys. Acta (2006) [Pubmed]
  7. Mechanism of polyamine tolerance in yeast: novel regulators and insights. Porat, Z., Wender, N., Erez, O., Kahana, C. Cell. Mol. Life Sci. (2005) [Pubmed]
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