the enzyme synthesizes docosahexaenoic acid-phosphatidylserine much more efficiently than phosphatidylserine containing either 18:1 or 20:4 at the sn-2 position. Although no sn-1 fatty acyl preference is noted, phosphatidylserine synthase 2 exhibits significant preference toward docosahexaenoic acid compared with 18:1 or 20:4 at the sn-2 position
the enzyme synthesizes docosahexaenoic acid-phosphatidylserine much more efficiently than phosphatidylserine containing either 18:1 or 20:4 at the sn-2 position. Although no sn-1 fatty acyl preference is noted, phosphatidylserine synthase 2 exhibits significant preference toward docosahexaenoic acid compared with 18:1 or 20:4 at the sn-2 position
the enzyme synthesizes docosahexaenoic acid-phosphatidylserine much more efficiently than phosphatidylserine containing either 18:1 or 20:4 at the sn-2 position. Although no sn-1 fatty acyl preference is noted, phosphatidylserine synthase 2 exhibits significant preference toward docosahexaenoic acid compared with 18:1 or 20:4 at the sn-2 position
the recombinant FLAG-tagged enzyme is also active with phosphatidylethanolamine plasmalogen, [C18(plasm),22:6-PS], which is six times less effective as a substrate than the corresponding ester-linked phosphatidylethanolamine species, the isozyme is active with oleic acid (OA; 18:1n-9), DHA (DHA; 22:6n-3), or arachidonic acid esters. Compounds analysis by mass spectroscopy. A carbonyl group next to the glycerol backbone in the substrate-binding pocket substantially increases the catalytic activity of PSS2. Isozyme PSS2 shows a 10fold preference for sn-1 18:0, when 22:6 is esterified at the sn-2 position. Synthesis of 18:0,22:6-PS is most efficient compared with 18:0,18:1-PS and with 18:0,20:4-PS. Substrate specificity and acyl chain preference of isozyme PS2, overview
the recombinant FLAG-tagged enzyme is also active with phosphatidylethanolamine plasmalogen, [C18(plasm),22:6-PS], which is six times less effective as a substrate than the corresponding ester-linked phosphatidylethanolamine species, the isozyme is active with oleic acid (OA; 18:1n-9), DHA (DHA; 22:6n-3), or arachidonic acid esters. Compounds analysis by mass spectroscopy. A carbonyl group next to the glycerol backbone in the substrate-binding pocket substantially increases the catalytic activity of PSS2. Isozyme PSS2 shows a 10fold preference for sn-1 18:0, when 22:6 is esterified at the sn-2 position. Synthesis of 18:0,22:6-PS is most efficient compared with 18:0,18:1-PS and with 18:0,20:4-PS. Substrate specificity and acyl chain preference of isozyme PS2, overview
the recombinant FLAG-tagged enzyme is also active with phosphatidylethanolamine plasmalogen, [C18(plasm),22:6-PS], which is six times less effective as a substrate than the corresponding ester-linked phosphatidylethanolamine species, the isozyme is active with oleic acid (OA; 18:1n-9), DHA (DHA; 22:6n-3), or arachidonic acid esters. Compounds analysis by mass spectroscopy. A carbonyl group next to the glycerol backbone in the substrate-binding pocket substantially increases the catalytic activity of PSS2. Isozyme PSS2 shows a 10fold preference for sn-1 18:0, when 22:6 is esterified at the sn-2 position. Synthesis of 18:0,22:6-PS is most efficient compared with 18:0,18:1-PS and with 18:0,20:4-PS. Substrate specificity and acyl chain preference of isozyme PS2, overview
isozyme PSS2 is expressed in a tissue-specific manner. It is highly expressed in tissues such as brain and testis, where docosahexaenoic acid (DHA, 22:6n-3) is also highly enriched
isozyme PSS2 is expressed in a tissue-specific manner. It is highly expressed in tissues such as brain and testis, where docosahexaenoic acid (DHA, 22:6n-3) is also highly enriched
isozyme PSS2 is expressed in a tissue-specific manner. It is highly expressed in tissues such as brain and testis, where docosahexaenoic acid (DHA, 22:6n-3) is also highly enriched
phosphatidylserine is synthesized in mammalian cells by two integral membrane proteins, PS synthase 1 and 2 (PSS1 and PSS2). These enzymes catalyze the formation of phosphatidylserine by an exchange reaction in which serine replaces the head group of the corresponding substrate phospholipids, phosphatidylcholine (PC) for isozyme PSS1 and phosphatidylethanolamine (PE) for isozyme PSS2
phosphatidylserine is synthesized in mammalian cells by two integral membrane proteins, PS synthase 1 and 2 (PSS1 and PSS2). These enzymes catalyze the formation of phosphatidylserine by an exchange reaction in which serine replaces the head group of the corresponding substrate phospholipids, phosphatidylcholine (PC) for isozyme PSS1 and phosphatidylethanolamine (PE) for isozyme PSS2
docosahexaenoic acid positively modulates phosphatidylserine biosynthesis. Over-expression of PSS2 alters neither the phosphatidylserine level nor the effect of docosahexaenoic acid on phosphatidylserine increase
expression of PSS2 in ethanolamine-requiring mutant Chinese hamster ovary cells defective in PSS1, reverses the ethanolamine auxotrophy. However, the phosphatidylethanolamine content is not normalized unless the culture medium is supplemented with ethanolamine. In both mutant chinese hamster ovary cells and hepatoma cells transfected with PSS2 cDNA the rate of synthesis of phosphatidylserine and phosphatidylserine-derived phosphatidylethanolamine does not exceed that in parental chinese hamster ovary cells or control McArdle cells, respectively. Expression of murine PSS2 in McArdle cells does not inhibit phosphatidylethanolamine synthesis via the CDP-ethanolamine pathway, whereas expression of similar levels of PSS1 activity inhibit this pathway by approx. 50%
intercrosses of mice lacking PSS1, EC 2.7.8.8, and PSS2-/- mice yield mice with three disrupted Pss alleles but no double knockout mice. In PSS1-/-PSS2+/- and PSS1+/-PSS2-/- mice, serine exchange activity is reduced by 65-91%,and the tissue content of phosphatidylserine and phosphatidylethanolamine is also decreased. Elimination of either PSS1 or PSS2, but not both, is compatible with mouse viability, mice can tolerate as little as 10% of normal total serine-exchange activity, and mice survive with significantly reduced phosphatidylserine and phosphatidylethanolamine content
the ability of testis extracts from PSS2-deficient mice to catalyze serine exchange is reduced by more than 95%, reductions of 90% are found in the brain and liver. There are no perturbations in the phospholipid content of any of these tissues. The expression of PSS1, EC 2.7.8.8, is not upregulated in Pss2-deficient cells and tissues. Testis weight is reduced in Pss2-deficient mice, and some of the male mice are infertile
the enzyme plays a key role in phosphatidylserine accumulation in brain and testis through high activity toward docosahexaenoic acid-containing substrates
isozyme PSS2 may play a key role in phosphatidylserine accumulation in brain and testis through high activity toward DHA-containing substrates that are abundant in these tissues