Nuclear envelope remnants are enriched in polyphosphoinositides.

<p>Lipid analysis of nuclear envelope remnants. (A) Lipids extracted from <i>L. pictus</i> demembranated sperm cells were separated by HPLC on a normal phase column and characterized by ESI-MS/MS using the precursor ion scans of sphingomyelin (SM), phosphatidylglycerol (PtdGly), phosphatidylethanolamine (PtdEth), phosphatidic acid (PtdAc), phosphatidylserine (PtdSer), phosphatidylcholine (PtdCho), phosphatidylinositol (PtdIns) or using the multiple ion scans of phosphatidylinositolphosphate (PtdInsP), phosphatidylinositolbisphosphate (PtdInsP₂) and phosphatidylinositoltrisphosphate (PtdInsP₃). Phospholipids were quantified using 12∶0/12∶0 (SM, PtdGly, PtdEth, PtdAc, PtdSer and PtdCho) or 16∶0/16∶0 (PtdIns, PtdInsP, PtdInsP₂ and PtdInsP₃) internal standards. Data expressed as mean±SEM (n = 3). (B) Alkyl-acyl versus diacyl phosphoinositides species distribution in nuclear envelope remnants. Mole percentages of diacyl species (green) and alkyl-acyl species (blue) were quantified from the multiple ion scans for each phosphoinositide class: PtdInsP, PtdInsP₂ and PtdInsP₃. 38% of PtdInsP, 15% of PtdInsP₂ and 49% of PtdInsP₃ are diacyl species. The PtdInsP₂ is predominantly alkyl-acyl phosphoinositide. Data expressed as mean±SEM (n = 3).