en
Scientific article
English

Microdomain-dependent regulation of Lck and Fyn protein-tyrosine kinases in T lymphocyte plasma membranes

Published inMolecular biology of the cell, vol. 10, no. 4, p. 891-905
Publication date1999
Abstract

Src family protein-tyrosine kinases are implicated in signaling via glycosylphosphatidylinositol (GPI)-anchored receptors. Both kinds of molecules reside in opposite leaflets of the same sphingolipid-enriched microdomains in the lymphocyte plasma membrane without making direct contact. Under detergent-free conditions, we isolated a GPI-enriched plasma membrane fraction, also containing transmembrane proteins, selectively associated with sphingolipid microdomains. Nonionic detergents released the transmembrane proteins, yielding core sphingolipid microdomains, limited amounts of which could also be obtained by detergent-free subcellular fractionation. Protein-tyrosine kinase activity in membranes containing both GPI-anchored and transmembrane proteins was much lower than in core sphingolipid microdomains but was strongly reactivated by nonionic detergents. The inhibitory mechanism acting on Lck and Fyn kinases in these membranes was independent of the protein-tyrosine phosphatase CD45 and was characterized as a mixed, noncompetitive one. We propose that in lymphocyte plasma membranes, Lck and Fyn kinases exhibit optimal activity when juxtaposed to the GPI- and sphingolipid-enriched core microdomains but encounter inhibitory conditions in surrounding membrane areas that are rich in glycerophospholipids and contain additional transmembrane proteins.

Keywords
  • Animals
  • Antibodies, Monoclonal
  • Antigens, CD26/metabolism
  • Antigens, CD45/metabolism
  • Cell Membrane/physiology
  • Glycosylphosphatidylinositols/metabolism
  • Kinetics
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/ metabolism
  • Lymphoma, T-Cell
  • Membrane Lipids/metabolism
  • Mice
  • Proto-Oncogene Proteins/ metabolism
  • Proto-Oncogene Proteins c-fyn
  • Rats
  • Signal Transduction
  • Sphingolipids/metabolism
  • T-Lymphocytes/ physiology
  • Tumor Cells, Cultured
Affiliation Not a UNIGE publication
Citation (ISO format)
ILANGUMARAN, Subburaj et al. Microdomain-dependent regulation of Lck and Fyn protein-tyrosine kinases in T lymphocyte plasma membranes. In: Molecular biology of the cell, 1999, vol. 10, n° 4, p. 891–905. doi: 10.1091/mbc.10.4.891
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ISSN of the journal1059-1524
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