Biochemical and molecular characterization of two phosphatidic acid-selective phospholipase A1s, mPA-PLA1alpha and mPA-PLA1beta

J Biol Chem. 2003 Dec 5;278(49):49438-47. doi: 10.1074/jbc.M213018200. Epub 2003 Sep 8.


We have identified a novel phospholipase A1, named mPA-PLA1beta, which is specifically expressed in human testis and characterized it biochemically together with previously identified mPA-PLA1alpha. The sequence of mPAPLA1beta encodes a 460-amino acid protein containing a lipase domain with significant homology to the previously identified phosphatidic acid (PA)-selective PLA1, mPA-PLA1alpha. mPA-PLA1beta contains a short lid and deleted beta9 loop, which are characteristics of PLA1 molecules in the lipase family, and is a member of a subfamily in the lipase family that includes mPA-PLA1alpha and phosphatidylserine-specific PLA1. Both mPA-PLA1beta and mPA-PLA1alpha recombinant proteins exhibited PA-specific PLA1 activity and were vanadate-sensitive. When mPAPLA1beta-expressing cells were treated with bacterial phospholipase D, the cells produced lysophosphatidic acid (LPA). In both mPA-PLA1alpha and beta-expressing cells, most of the PA generated by the phospholipase D (PLD) treatment was converted to LPA, whereas in control cells it was converted to diacylglycerol. When expressed in HeLa cells most mPA-PLA1alpha protein was recovered from the cell supernatant. By contrast, mPA-PLA1beta was recovered almost exclusively from cells. Consistent with this observation, we found that mPA-PLA1beta has higher affinity to heparin than mPA-PLA1alpha. We also found that the membrane-associated mPA-PLA1s were insoluble in solubilization by 1% Triton X-100 and were detected in Triton X-100-insoluble buoyant fractions of sucrose gradients. The present study raises the possibility that production of LPA by mPA-PLA1alpha and -beta occurs on detergent-resistant membrane domains of the cells where they compete with lipid phosphate phosphatase for PA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Blotting, Western
  • Cell Line
  • Diglycerides / biosynthesis
  • Fluorescent Antibody Technique
  • Humans
  • Mass Spectrometry
  • Molecular Sequence Data
  • Phosphatidic Acids / biosynthesis
  • Phosphatidic Acids / metabolism*
  • Phospholipases A / chemistry
  • Phospholipases A / genetics
  • Phospholipases A / metabolism*
  • Phospholipases A1
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Spodoptera
  • Substrate Specificity
  • Vanadates / pharmacology


  • Diglycerides
  • Phosphatidic Acids
  • Recombinant Proteins
  • Vanadates
  • Phospholipases A
  • Phospholipases A1

Associated data

  • GENBANK/AY197607