FIGURE 7.

Arr3 peptides derived from the L-PGDS binding domain enhance PGD₂ production by L-PGDS. A, shown is a schematic representation of peptides synthesized and used in PGD₂ production in vitro assays. His₆-L-PGDS was incubated with equivalent molar ratio of pRSETa, purified His₆-Arr3, or indicated synthetic peptides, and PGD₂ production was stimulated by the addition of 0.5 μm PGH₂ (L-PGDS substrate) for 1 min. Reactions were stopped with 0.4 mg/ml SnCl₂, and PGD₂ was then measured with commercial enzyme-linked immunoassays. B, shown is a schematic representation of TAT peptides synthesized and used in PGD₂ production in cells. MG-63 cells were preincubated with 100 μm TAT-Scrambled (Scr) or TAT-Arr3 amino acid 86–100 peptides for 1 h and with 100 μm HQL-79 (H-PGDS inhibitor, to specifically measure L-PGDS activity) for 15 min. Cells were then incubated with 5 μm PGH₂ (L-PGDS substrate) for 15 min. Supernatants were assessed for PGD₂ production by commercial enzyme-linked immunoassays as described under “Experimental Procedures.” All values are the mean ± S.E. from at least three separate experiments. **, p < 0.05; ***, p < 0.001.