Traffic, polarity, and detergent solubility of a glycosylphosphatidylinositol-anchored protein after LDL-deprivation of MDCK cells

Lisa A. Hannan, Michael Edidin

Research output: Contribution to journalArticle

Abstract

Glycosylphosphatidylinositol-anchored proteins, GPI-proteins, are selectively delivered to the apical surfaces of many types of morphologically polarized epithelial cells. It has been proposed that the unit for targeting GPI-proteins to the apical surface is a membrane lipid domain. This sorting domain or molecular cluster has been equated to detergent (Triton X- 100)insoluble membrane fractions that are enriched in enriched in GPI- proteins, glycosphingolipids, and cholesterol. To determine the role of cholesterol in the formation of sorting domains and to examine its importance in the intracellular traffic and membrane polarity of GPI-proteins, we studied the behavior of a model GPI-protein, gD1-DAF, in MDCK cells cultured for 3 or 14 d without their principal source of cholesterol, serum LDL. LDL deprivation affects the intracellular traffic of gD1-DAF. Surface expression of gD1-DAF is reduced in LDL-deprived cells; this reduction is most marked after 3 d of LDL deprivation. We also find a great reduction in the fraction of gD1-DAF that is detergent-insoluble in these cells and a change in its membrane milieu defined by susceptibility to cleavage with PI-specific phospholipase C. Despite these changes, the surface polarity of gD1-DAF is no different in LDL-deprived cells than in control cells.

Original languageEnglish (US)
Pages (from-to)1265-1276
Number of pages12
JournalJournal of Cell Biology
Volume133
Issue number6
DOIs
StatePublished - Jul 5 1996

ASJC Scopus subject areas

  • Cell Biology

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