Affiliation:
1. Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218.
Abstract
Glycosyl-phosphatidylinositol (GPI)-anchored proteins are sorted to the apical surface of many epithelial cell types. To better understand the mechanism for apical segregation of these proteins, we analyzed the lateral mobility and molecular associations of a model GPI-anchored protein, herpes simplex virus gD1 fused to human decay accelerating factor (gD1-DAF) (Lisanti, M. P., I. W. Caras, M. A. Davitz, and E. Rodriguez-Boulan. 1989. J. Cell Biol. 109:2145-2156) shortly after arrival and after long-term residence at the surface of confluent, polarized MDCK cells. FRAP measurements of lateral diffusion showed that the mobile fraction of newly arrived gD1-DAF molecules was much less than the mobile fraction of long-term resident molecules (40 vs. 80-90%). Fluorescence resonance energy transfer measurements showed that the newly arrived molecules were clustered, while resident molecules were not. Newly delivered gD1-DAF molecules were clustered but not immobilized in mutant, Concanavalin A-resistant MDCK cells that failed to sort gD1-DAF. Our results indicate that GPI-anchored proteins in MDCK cells are clustered before delivery to the surface. However, clustering alone does not target molecules for apical delivery. The immobilization observed when gD1-DAF is correctly sorted suggests that the clusters must associate some component of the cell's cytoplasm.
Publisher
Rockefeller University Press
Cited by
112 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献