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Updated: Oct 1, 2026

Fluorescence-Based Measurements of Phosphatidylserine/Phosphatidylinositol 4-Phosphate Exchange Between Membranes
Published on: March 14, 2021
Mechanisms of substrate recognition and catalysis in a mammalian phosphatidylserine synthase 2
Lie Wang1, Zhen Zhang1, Hongyuan Yang2
1Verna and Marrs McLean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX 77030.
Abstract:
Mammalian phosphatidylserine synthase-1 and -2, PSS1 and PSS2, synthesize phosphatidylserine (PS) by replacing the headgroup of either phosphatidylcholine or phosphatidylethanolamine (PE) with a serine. We determined structures of PSS2 from Equus caballus in complex with either a PE or a serine substrate to resolutions of 2.8 to 3.2 Å. The structures define substrate binding sites and reveal that the phosphate group of the PE is coordinated by two Ca2+. In addition, we found that PSS2 has significant phospholipase D (PLD) activity in the absence of serine and that Ca2+ is required for the PLD activity. These findings enrich and refine our knowledge in the mechanisms of substrate recognition and catalysis in mammalian PSS.
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