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Nem1p‐Spo7p‐mediated dephosphorylation of yeast Pah1p phosphatidate phosphatase
Author(s) -
Su WenMin M.,
Han GilSoo,
Carman George M
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.822.4
Subject(s) - phosphatidate , dephosphorylation , diacylglycerol kinase , biochemistry , phosphatase , phosphatidic acid , phosphorylation , cytosol , chemistry , biology , enzyme , microbiology and biotechnology , membrane , protein kinase c , phospholipid
Yeast Pah1p phosphatidate phosphatase (PAP), which catalyzes the dephosphorylation of phosphatidate to yield diacylglycerol and Pi, has emerged as one of the most important and highly regulated enzymes in lipid metabolism. The enzyme controls the cellular amounts of phosphatidate and diacylglycerol, which in turn regulate the synthesis of phospholipids and neutral lipids through genetic and biochemical mechanisms. Because Pah1p is principally located in the cytosol, its association with the nuclear/ER membrane where the substrate phosphatidate resides is essential to PAP function in vivo . The association of Pah1p with the membrane is regulated by the phosphorylation state of the enzyme; phosphorylated Pah1p is mainly found in the cytosol, whereas dephosphorylated Pah1p is mainly associated with the membrane. The phosphorylated enzyme is recruited to the membrane where it is dephosphorylated by the Nem1p‐Spo7p phosphatase complex. This dephosphorylation leads to anchoring of Pah1p to the membrane allowing for the PAP reaction and triacylglycerol synthesis. The enzymological properties (pH optimum, divalent cation dependence, kinetics) of the Nem1p‐Spo7p‐mediated dephosphorylation was examined in a well‐defined system using the purified phosphatase complex and purified Pah1p that was phosphorylated with the Pho85p‐Pho80p protein kinase‐cyclin complex. Supported by NIH grant GM‐50679.