Research ResourceCell Cycle

Quantitative phosphoproteomics reveals new roles for the protein phosphatase PP6 in mitotic cells

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Sci. Signal.  13 Oct 2015:
Vol. 8, Issue 398, pp. rs12
DOI: 10.1126/scisignal.aab3138

Exploring mitotic phosphatase function

To study the function of the serine-threonine protein phosphatase PP6, Rusin et al. analyzed the effect of depleting HeLa cells of the catalytic subunit of PP6 on the phosphoproteome when the cells were arrested in mitosis. Motif analysis of the sequences of the sites that changed in the PP6c-depleted cells suggested kinases that PP6 activity may oppose. In addition to the known role of PP6 in reducing the activity of the Aurora kinase A, a kinase that is important for chromosome segregation and spindle formation, network analysis of the proteins that exhibited differences in phosphorylation identified roles for PP6 in the regulation of RNA splicing, rRNA processing, and translation. Biochemical analysis showed that a subunit of the complex necessary for chromosome condensation was phosphorylated by casein kinase 2 and dephosphorylated by PP6. Thus, this study identified a mitotically regulated phosphorylation event in this critical complex and provided many other potential direct substrates of PP6 and pathways regulated by PP6 in mitotic cells.