High impact information on SAT4

• Genetic evidence indicates that Trk1p is activated by the Hal4 and -5 kinases and inhibited by the Ppz1 and -2 phosphatases, which, in turn, are inhibited by their regulatory subunit, Hal3p [1].
• Interestingly, the Spc1-Hal4 interaction appears to be required for cellular resistance to Ca(2+) but not Na(+) and Li(+) [2].
• The hal4-null phenotype is complemented by overexpression of the Trk1 potassium transporter or increased K(+) in the growth medium, suggesting that Hal4 promotes K(+) uptake, which consequently increases cellular resistance to other cations [2].
• We have characterized two partially redundant genes from Saccharomyces cerevisiae, HAL4/SAT4 and HAL5, that encode homologous protein kinases implicated in the regulation of cation uptake [3].
• These results are consistent with a model in which ARL1, via regulation of HAL4/HAL5, governs K(+) homeostasis in cells [4].

Biological context of SAT4

• Our data support a role for regulation of membrane potential in adaptation to salt stress that is mediated by the Hal4 and Hal5 kinases [3].
• Hal4 shares sequence homology to Hal4 and Hal5 in S. cerevisiae, and previous evidence indicates that these kinases positively regulate the major potassium transporter Trk1,2 and thereby maintain the plasma membrane potential [5].
• The open reading frame YCR101 located on chromosome III from Saccharomyces cerevisiae is a putative protein kinase [6].

Anatomical context of SAT4

• We demonstrate that a mutation in hal4+ results in hyperpolarization of the plasma membrane [5].

Associations of SAT4 with chemical compounds

• Like its budding yeast counterpart, the fission yeast Hal4 kinase is essential for cellular resistance to Na(+), Li(+), and Ca(2+) [2].

Other interactions of SAT4

• YCR8W (encoding a putative protein kinase) and YCR14C extend inside the D10H (Skala et al., 1991) and 62B5-2D clones respectively [7].

References