Comparative studies on internalization of gold-labelled mistletoe lectin I, its subunits, as well as of an immunotoxin in murine L 1210 leukemia cells.
The binding and internalization of gold-labelled mistletoe lectin I (ML I), its A (ML I-A) and B (ML I-B) subunits, as well as of an immunotoxin consisting of an monoclonal anti L 1210 antibody and the cytotoxic A chains of ML I, were studied on murine L 1210 leukemia cells by a preembedding electron microscopic technique. We found that receptor-mediated endocytosis differs remarkably between the whole lectin, its subunits, and the immunotoxin. Whereas ML I, its A chain, as well as the immunotoxin are internalized by coated pits/coated vesicles or in combination with uncoated membranes, the B chain is exclusively endocytosed via uncoated deep invaginations of the cell membrane. The endocytosis via clathrin-coated or uncoated vesicles is discussed taking into account the binding and internalization kinetics of ligand-receptor complexes related with the movement by the cytoskeleton.
Jonas
L
L
Department of Pathology, University of Rostock, Germany.
Walzel
H
H
D000818:Animals; D002846:Chromatography, Affinity; D003600:Cytosol / Q000378:metabolism; D004705:Endocytosis; D007150:Immunohistochemistry; D000922:Immunotoxins / Q000378:metabolism*; D007700:Kinetics; D007939:Leukemia L1210 / Q000378:metabolism*; D051379:Mice; D008811:Mice, Inbred DBA; D008854:Microscopy, Electron; D015388:Organelles / Q000378:metabolism; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000378:metabolism
D000922:Immunotoxins; D028321:Plant Preparations; D010940:Plant Proteins; D054790:Ribosome Inactivating Proteins, Type 2; D014118:Toxins, Biological; C488862:mistletoe lectin I; C009674:ribosome inactivating protein, Viscum