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R3499 --> 818.7 --> Pah1 PA phosphatase catalyzes the dephosphorylation of PA to produce diacylglycerol. In yeast and higher eukaryotes, the diacylglycerol produced in the reaction is used for the synthesis of triacylglycerol or the membrane phospholipids phosphatidylcholine and phosphatidylethanolamine. Pah1 is inactive as a phosphorylated enzyme in the cytosol and becomes active after its recruitment and dephosphorylation by the ER‐associated Nem1‐Spo7 protein phosphatase complex. Conserved N‐LIP and HAD‐like domains are required for PA phosphatase activity and a conserved tryptophan within the WRDPLVDID domain is required for its in vivo function in lipid metabolism. Intrinsically disordered regions, which are located between the conserved catalytic domains and at the C terminus, contain multiple sites for phosphorylation and regulation of Pah1 location and function. Prediction of Pah1 structure by AlphaFold identifies a novel domain contained within the N‐terminal intrinsically disordered region for which its function is unknown. A truncation mutant that lacks amino acid residues 186‐266 have been constructed and expressed in a pah1D and pah1D nem1D mutants to assess the function of the novel domain for regulating Pah1 phosphorylation, recruitment and dephosphorylation by the Nem1‐Spo7 protein phosphatase complex, and function in lipid metabolism. [ABSTRACT FROM AUTHOR]

R3079 --> 818.4 --> The yeast phosphatidic acid (PA) phosphatase, Pah1, regulates the synthesis of triacylglycerol (TAG) and phospholipids by controlling the relative amounts of its substrate PA and product diacylglycerol. Pah1 phosphorylation, which is mediated by multiple protein kinases, has been shown to protect the protein against proteasomal degradation and regulates its localization and catalytic activity. Phosphorylated Pah1 is cytoplasmic, but it translocates to the nuclear/endoplasmic reticulum membrane for catalytic function through its dephosphorylation. In this study, we show that Rim11, a yeast homolog of glycogen synthase kinase phosphorylates Pah1. The rim11Δ mutant shows alterations in lipid composition with elevated TAG levels during exponential growth, the phase in which Rim11 is the most abundant. Rim11 purified from yeast phosphorylated Escherichia coli‐expressed Pah1, which lacks endogenous phosphorylation, in a manner that is dependent on reaction time and the amounts of Rim11, Pah1, and ATP. Phosphoamino acid analysis and phosphopeptide mapping showed that Pah1 phosphorylation by Rim11 occurs at multiple serine and threonine residues, which was supported by mass spectrometry analysis which indicated that Rim11 has a major phosphorylation site that is shared with multiple kinases (Ser‐602) and two unique minor phosphorylation sites (Thr‐163 and Thr‐164). Furthermore, in vitro PA phosphatase assays show that Pah1 catalytic activity is inhibited following phosphorylation by Rim11. [ABSTRACT FROM AUTHOR]

R400 --> 677.1 --> The Nem1‐Spo7/Pah1 phosphatase cascade plays an essential role in the synthesis of the neutral lipid triacylglycerol in the yeast Saccharomyces cerevisiae. Pah1 is a phosphatidic acid (PA) phosphatase that is phosphorylated and inactive in the cytoplasm. The Nem1‐Spo7 complex is a nuclear/endoplasmic reticulum (ER)‐associated protein phosphatase that recruits, dephosphorylates, and activates Pah1. Upon its dephosphorylation, Pah1 hops onto the membrane surface for its interaction with and dephosphorylation of PA to produce the diacylglycerol that is then converted to triacylglycerol. Pah1 then scoots along the membrane to associate with and dephosphorylate another PA molecule. In this work, the Nem1‐Spo7 complex was reconstituted into unilamellar phospholipid vesicles (proteoliposomes) composed of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and PA to mimic the nuclear/ER membrane. The phospholipid composition of the proteoliposomes, which had an average diameter of 60 nm, was confirmed by thin‐layer chromatography. The reconstituted Nem1‐Spo7 complex supported the recruitment and dephosphorylation of Pah1 phosphorylated by the Pho85‐Pho80 protein kinase complex in vitro or the Pah1 phosphorylated by multiple protein kinases in vivo. The Nem1‐Spo7‐mediated dephosphorylation of Pah1 was dependent on the presence of PA in the proteoliposomes. Additionally, the dephosphorylated Pah1 catalyzed the dephosphorylation of PA to produce diacylglycerol in the proteoliposomes. This reconstituted system permits a defined membrane environment to examine the regulation of the Nem1‐Spo7/Pah1 phosphatase cascade. [ABSTRACT FROM AUTHOR]

Abstract: Lipin-1 proteins are phosphatidic acid phosphatases (PAPs) catalyzing the conversion from phosphatidic acid (PA) to diacylglycerol (DG). Two alternative splicing isoforms, lipin-1α and -1β, are localized at different subcellular compartments. A third splicing isoform, lipin-1γ was recently cloned and its subcellular localization is unknown. Here, we demonstrate that lipin-1γ is localized to lipid droplets (LDs), an association mediated by a hydrophobic, lipin-1γ-specific domain. Additional expression of lipin-1γ altered LD morphology without affecting the triacylglycerol (TG) level. In human tissues, lipin-1γ is the main lipin-1 isoform expressed in normal human brain, suggesting a specialized role in regulating brain lipid metabolism. [Copyright &y& Elsevier]

The aim of this study was to identify the factors that influence foreign doctors’ community integration and examine how these affect their intention to stay in the rural community. Qualitative study using life-history perspective. Rural communities throughout Victoria. Fifty-seven overseas-trained doctors (OTDs) working throughout rural Victoria, Australia. Key factors of community integration influencing OTDs’ decision to stay in or leave a rural community. Maintaining cultural and religious values, as well as relationships to their respective ethnic communities is important to OTDs. While they do not expect excessive support from the community they appreciated the cultures of welcoming or ‘embracing differences’. Supportive communication and supervisory support positively influence OTDs’ appreciation of what the rural community can offer them and how they might overcome any difficulties that they face with their rural practice and life. As well as ensuring that OTDs’ professional needs are met, the importance of a supportive environment within the clinic and community awareness of the OTDs’ needs should not be underestimated as influences on an OTD's retention in a rural community. [ABSTRACT FROM AUTHOR]

R2436 --> The yeast phosphatidic acid (PA) phosphatase, Pah1, regulates the synthesis of triacylglycerol and phospholipids by controlling the relative amounts of its product diacylglycerol and substrate PA. Pah1 is cytosolic as a phosphoprotein, but translocates to the nuclear/endoplasmic reticulum membrane for catalytic function through its dephosphorylation. The phosphorylation of Pah1, which is mediated by multiple protein kinases, has been shown to protect the protein against proteasomal degradation and regulates its catalytic activity. In this study, we show that Rim11, a yeast homolog of glycogen synthase kinase (GSK) known for its role in meiotic induction, is involved in the phosphorylation of Pah1. Rim11 purified from yeast phosphorylated the Escherichia coli‐expressed Pah1, which is phosphorylation‐deficient, in a manner that is dependent on reaction time and the amounts of Rim11, Pah1, and ATP. Phosphoamino acid analysis and phosphopeptide mapping showed that Pah1 phosphorylation by Rim11 occurs at multiple serine residues. As GSKs are known to require priming phosphorylation, we are examining the Rim11 phosphorylation of Pah1 that is pre‐phosphorylated by other protein kinases. [ABSTRACT FROM AUTHOR]

Lipin 1 plays an important role in fat metabolism in mammalian cells. Its deficiency causes lipodystrophy, whereas its excess causes obesity. Recent studies identified the molecular function of lipin 1 as a Mg2+-dependent phosphatidate (PA) phosphatase enzyme. In this work, we examined the enzymological properties of His6-tagged human lipin 1 expressed in Escherichia coli. The PA phosphatase activity of lipin 1 was dependent on magnesium ions with optimal activity at 0.5 mM MgCl2. The pH optimum for the reaction was between 7.0 and 7.5. PA phosphatase activity followed surface dilution kinetics with respect to PA (Km = 5 mol%) using Triton X-100-PA mixed micelles. Lipin 1 enzyme activity was potently inhibited by N-ethylmaleimide with an IC50 value of 50 µM. Within a conserved C-terminal domain of lipin 1 is a DxDxT catalytic motif that is found in a superfamily of Mg2+-dependent phosphatase enzymes. Mutational analysis showed that lipin 1 proteins with aspartate-to-glutamate mutations (D678E and D680E) are catalytically inactive, confirming that the conserved aspartate residues are essential for Mg2+-dependent PA phosphatase activity. [ABSTRACT FROM AUTHOR]

Background and Objective: The use of radioiodine (RI) for the ablation of residual thyroid tissue and metastatic thyroid cancer lesions after thyroidectomy has become established as standard treatment in the management of differentiated thyroid cancer and subsequent sialadenitis is the most common complication of RI therapy. The purpose of this study was to establish a new treatment modality for RI-induced sialadenitis., Method: The study group consisted of 115 patients with a mean age of 47.7 (range, 24-78) years. All patients received RI therapy after total thyroidectomy. The incidence of RI-induced sialadenitis, salivary gland involvement, administered RI dose, treatment modality, and result of treatment by interventional sialoendoscopy were evaluated., Results: The incidence of RI-induced sialadenitis was 18% (21/115), with involvement of the parotid more frequent than the submandibular gland. The average development period of RI-induced sialadenitis was 4.8 months. The average RI dosage for the sialadenitis group was higher than for the nonsialadenitis group, suggesting that RI-induced sialadenitis may be dose related, although the data were not statistically significant because of the small numbers in the high-dose group. Conservative management was effective in 71% (15/21) of the cases, and interventional sialoendoscopy was successful in 50% of those cases that did not respond to conservative treatment. The causes of treatment failure in the remaining cases were a totally obstructed parotid duct and stenosis at the bifurcation site., Conclusion: Sialadenitis is the most common complication after RI therapy. Sialadenitis was successfully managed by conservative treatment in most cases, and interventional sialoendoscopy is an alternative method of treatment in selected cases such as in partial ductal stenosis.