High impact information on SAK1

• Septin collar formation in budding yeast requires GTP binding and direct phosphorylation by the PAK, Cla4 [1].
• Pak1 protein kinase regulates activation and nuclear localization of Snf1-Gal83 protein kinase [2].
• Pak1 associates with the Snf1 kinase in vivo, and the association is greatly enhanced under glucose-limiting conditions when Snf1 is active [3].
• The transmission of the mating signal of the budding yeast Saccharomyces cerevisiae requires Ste20p, a member of the serine/threonine protein kinases of the Ste20p/PAK family, to link the Gbeta subunit of the heterotrimeric G protein to the mitogen-activated protein kinase cascades [4].
• The p21-activated kinase (PAK) homolog Shk1 is essential for cell viability in the fission yeast Schizosaccharomyces pombe [5].

Biological context of SAK1

• Deletion of the PAK1 gene does not produce a Snf phenotype, suggesting that one or more additional protein kinases is able to activate Snf1 in vivo [3].
• Gene disruption of PAK1 indicates that it is not an essential gene [6].
• Pak1 may function by modifying and partially stabilizing thermolabile DNA polymerases, perhaps during DNA repair, because pak1 mutant cells are caffeine sensitive [6].
• Overexpression and suppression can be achieved either by expressing PAK1 from a high-copy-number plasmid, or by GAL1-induced transcription of PAK1 [6].
• The deletion of 43 amino acids from within the N terminus of Sak1 (residues 87 to 129) completely blocks Snf1 signaling and activation loop phosphorylation in vivo [7].

Associations of SAK1 with chemical compounds

• Three kinases, Pak1, Elm1, and Tos3, activate Snf1 by phosphorylation of its activation-loop threonine, and the absence of all three causes the Snf(-) phenotype [8].

Other interactions of SAK1

• Here we present evidence that the yeast Pak1 kinase functions as a Snf1-activating kinase [3].
• Overexpression of PAK1 does not enhance the expression of the POL1 gene [6].
• These kinases, Sak1, Tos3 and Elm2 do not appear to require the presence of additional subunits for activity [9].
• Thus, the C-terminal domains of Sak1, Tos3, and Elm1 help to determine pathway specificity [7].

Analytical, diagnostic and therapeutic context of SAK1

• Sak1 and Snf1 co-purify and co-elute in size exclusion chromatography, demonstrating that these two proteins form a stable complex [9].

References