High impact information on Psph

• To explore the mechanism of the diabetes-induced increases in the GLUT-4 phosphorylation, we investigated phosphoserine phosphatase (PSPase) activities using 32P-labeled GLUT-4 and phosphorylase "a" as substrates [1].
• The inhibition of PSPase was accompanied by a 60% increase in adipocytes (p less than 0.05) and a 118% increase (p less than 0.01) in skeletal muscle inhibitor 1 (I1) activities, respectively [2].
• PTPase activity was assessed with [32P]tyrosine-phosphorylated insulin receptor (IR), whereas PSPase activity was assayed with [32P]serine-phosphorylated glycogen synthase [3].
• We examined the activities of particulate and cytosolic phosphotyrosine phosphatase (PTPase) and phosphoserine phosphatase (PSPase) in adipocytes and livers of diabetic rats [3].
• Application of protein serine/threonine phosphatase (PSP) inhibitors prevented pCREB dephosphorylation and blocked the decreases in Aanat mRNA levels, AANAT protein amount and melatonin biosynthesis all of which occurred rapidly after NE withdrawal [4].

Biological context of Psph

• The rate-limiting step in the synthesis of serine is the hydrolysis of phosphoserine by phosphoserine phosphatase (EC 3.1.3.3) [5].
• Measurement on the 22nd day of gestation showed that the increases in phosphoserine phosphatase activity and glycine content were present in brain stem, cerebellum, and forebrain [6].
• Glycerylphosphorylcholine (IC50 18 microM) was found to be an uncompetitive inhibitor of phosphoserine phosphatase [7].

Anatomical context of Psph

• Differential effects of diabetes on adipocyte and liver phosphotyrosine and phosphoserine phosphatase activities [3].
• In conclusion, these studies demonstrate that phosphoserine phosphatase may be an important enzyme in regulating the steady-state levels of D-serine in neocortical synaptosomes [5].
• Of twelve enzymes quantified in the brains of hyperphenylalaninemic fetuses only phosphoserine phosphatase showed any change [6].

Associations of Psph with chemical compounds

• Serine hydroxy-methyltransferase and phosphoserine phosphatase activity in the liver were unaffected 6 days after castration [8].
• After day 3 of treatment there were persistent elevations in the specific activity of phosphoserine phosphatase and glycine synthase (but not serine hydroxymethyltransferase) of the brain in each of the regions analysed [9].
• The lack of stereospecificity for synaptosomal hydrolysis of phosphoserine and the inhibitory actions of AP3 are consistent with the presence of phosphoserine phosphatase in synaptosomes and further indicate that epimerization of serine can occur during or subsequent to the hydrolysis of L-phosphoserine but not D-phosphoserine [5].
• A significant decrease in the specific activity of 3 enzymes of serine and one-carbon metabolism (3-phosphoglycerate dehydrgenase, phosphoserine phosphatase, and serine hydroxy-methyltransferase) was found in the rat prostate gland with castration [8].
• Experiments with both intact and lysed synaptosomal preparations demonstrated hydrolysis of D-phosphoserine to only D-serine and inhibition of hydrolysis by the phosphoserine phosphatase inhibitor 2-amino-3-phosphonopropionic acid (AP3) [5].

Other interactions of Psph

• Insulin therapy for 14 or 30 days restored PTPase and PSPase activities in both fractions [3].
• The enzymes of the "phosphorylated pathway" of serine biosynthesis, i.e., 3-phosphoglycerate dehydrogenase, phosphoserine aminotransferase and phosphoserine phosphatase are present in rat brain as well as in rat astroglia-rich primary cultures and their specific activities have been determined [10].

References