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Resolution of multiple endosomal compartments associated with the internalization of epidermal growth factor and transferrin
Author(s) -
Gorman Regina M.,
Poretz R. D.
Publication year - 1987
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041310204
Subject(s) - internalization , endosome , transferrin , microbiology and biotechnology , transferrin receptor , epidermal growth factor , endocytosis , epidermal growth factor receptor , biology , chemistry , intracellular , cell culture , biochemistry , genetics , cell , receptor
Morphological studies have indicated divergent pathways for the endocytosis of epidermal growth factor (EGF) and transferrin (Tf). In order to obtain biochemical evidence for the pathways associated with the endocytosis of EGF and Tf, a series of Percoll density gradients were employed to separate individual cellular components. Subcellular fractionation of murine fibro‐blasts exposed to a 2‐min pulse of either 125 l‐Tf or 125 I‐EGF results in the detection of a total of six cellular compartments related to the internalization process of these ligands. The results of kinetic analysis of the entry of EGF into five membranous fractions is consistent with a model in which ligand is transferred sequentially from the plasma membrane through three distinct prelysosomal environments prior to reaching secondary lysosomes. Each prelysosomal compartment exhibits distinct density and temporal properties in a Percoll density gradient and may represent preexisting endocytic vesicles and/or specific domains of a continuous tubular structure, vesicularized during the process of cell disruption. In addition, the observed differential migration on Percoll density gradients of Tf and EGF containing compartments indicates that the majority of cell bound Tf segregates from EGF and enters a compartment lacking EGF within 5 min of internalization.