Expression and functional characterization of the P-selectin glycoprotein ligand-1 in various cells
Fujimoto, T.T.; Noda, M.; Takafuta, T.; Shimomura, T.; Fujimura, K.; Kuramoto, A.
International Journal of Hematology 64(3-4): 231-239
1996
ISSN/ISBN: 0925-5710 PMID: 8923785 Document Number: 458142
We have examined the expression and function of P-selectin glycoprotein ligand-1 (PSGL-1), which is a high affinity ligand for P-selectin. Northern blot and flow cytometric analysis demonstrated that a variety of hematopoietic cells and cell lines expressed PSGL-1. However, P-selectin binding ability was dependent on the additional expression of a carbohydrate structure, sialyl Lewis x (sLe-x). All the peripheral lymphocytes expressed PSGL-1 and subpopulation expressed sLe-x. Two color analysis showed that the majority of the cells that bound P-selectin were sLe-x-negative T lymphocytes, and most of the sLe-x-positive cells were B lymphocytes that did not bind P-selectin, indicating that the carbohydrate on T lymphocytes recognized by P-selectin is not sLe-x, and that the sLe-x on B lymphocytes is not readily presented for P-selectin recognition. Transfected 293 cells detectably bound P-selectin only when the cells expressed both PSGL-1 and sLe-x. When cysteine 310 of PSGL-1 was mutated to alanine, P-selectin binding was markedly reduced, suggesting the importance of dimerization of PSGL-1. These findings indicate that a preferable conformation of both carbohydrate and protein structure is necessary for a functional P-selectin ligand.