Although human group VIB calcium-independent phospholipase A2 (iPLA2γ) contains the lipase-consensus sequence Gly-Xaa-Ser-Xaa-Gly in the C-terminal half, its overall sequence exhibits a week similarity to those of other PLA2s, and thus no information on the catalytic site has been available. Here we show that the C-terminal region of human iPLA2γ is responsible for the enzymatic activity. Comparison of this catalytic domain with those of the mouse homologue, human cytosolic PLA2 (cPLA2), and the plant PLA2 patatin reveals that an amino acid sequence of a short segment around Asp-627 of iPLA2γ is conserved among these PLA2s, in addition to the Ser-483-containing lipase motif; the corresponding serine and aspartate in cPLA2 and patatin are known to form a catalytic dyad. Since substitution of alanine for either Ser-483 or Asp-627 results in a loss of the PLA2 activity, we propose that Ser-483 and Asp-627 of human iPLA 2γ constitute an active site similar to the Ser-Asp dyad in cPLA2 and patatin.
|Number of pages||7|
|Journal||Biochemical and Biophysical Research Communications|
|Publication status||Published - Aug 6 2004|
All Science Journal Classification (ASJC) codes
- Molecular Biology
- Cell Biology