Figure 6.

Analysis of the endosomal sorting activity in P-selectin by alanine scanning mutagenesis of the C1 region. Each of the amino acid residues in the C1 region of P-selectin was substituted with alanine by site-directed mutagenesis and expressed in NRK cells. In addition, the glycine at position 764 was substituted with valine (G764V), and the prolines at positions 767 and 770 were substituted with alanine concomitantly (P767A/P770A). Half-lives of the mutants and of transferrin receptor (TfR) and of wild-type P-selectin (wt) were measured after biotin labeling of the cell surface as described in the legend of Figure 4. Only substitution of L768 with alanine caused a significant increase in the half-life of P-selectin.