Internalization of Glycosyl-Phosphatidylinositol (GPI)-anchored Lymphocyte Proteins. II. GPI-anchored and Transmembrane Molecules Internalize Through Distinct Pathways

Eur J Immunol. 1992 Jan;22(1):15-21. doi: 10.1002/eji.1830220104.

Abstract

Ly-6A.2 (T cell-activating protein, TAP) and Thy-1 are glycosyl-phosphatidyl-inositol (GPI)-anchored proteins expressed on the surface of murine T lymphocytes. We have found that Ly-6A.2 (TAP) and Thy-1 are internalized by T cells. In the present study we have investigated whether these GPI-anchored proteins enter cells by endocytosis through coated pits. Two lines of evidence argue against the involvement of coated pits in the internalization of Ly-6A.2 (TAP) and Thy-1. First, drugs that effectively blocked the endocytosis of transferrin receptor and H-2 class I molecules, (which are known to be internalized via coated pits) did not inhibit the internalization of the GPI-anchored proteins. Second, in ultrastructural analyses, Ly-6A2 (TAP) and Thy-1, in contrast to the transferrin receptor, were rarely found in coated pits or vesicles. These observations suggest that the GPI-anchored proteins on T lymphocytes are internalized by a distinct pathway that does not involve endocytosis through coated pits.

MeSH terms

  • Animals
  • Antigens, Ly / metabolism
  • Antigens, Surface / metabolism
  • Cell Line
  • Ethylmaleimide / pharmacology
  • Glycolipids / metabolism*
  • Glycosylphosphatidylinositols
  • H-2 Antigens / metabolism
  • Kinetics
  • Membrane Proteins / metabolism*
  • Mice
  • Phosphatidylinositols / metabolism*
  • Receptors, Cell Surface / physiology
  • Receptors, Cytoplasmic and Nuclear*
  • Receptors, Transferrin / metabolism
  • T-Lymphocytes / metabolism*
  • Thy-1 Antigens

Substances

  • Antigens, Ly
  • Antigens, Surface
  • Glycolipids
  • Glycosylphosphatidylinositols
  • H-2 Antigens
  • Membrane Proteins
  • Phosphatidylinositols
  • Receptors, Cell Surface
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Transferrin
  • Thy-1 Antigens
  • phosphatidylinositol receptors
  • Ethylmaleimide