title: [The dependence of the type of endocytosis of EGF receptor complexes on the basal level of tyrosine kinase activity in the epidermal growth factor receptor].
abstract: Two types of EGF-mediated endocytosis have been identified in A431 cells by the method of subcellular fractionation in Percoll density gradients. One ("slow") type of endocytosis is characterized by 125I-EGF retention in the fraction of light endosomes, while the other ("fast") type demonstrates efficient 125I-EGF transition into heavy endosomes and lysosomes. 32P-ATP phosphorylation assay of Percoll fractions, followed by alkaline treatment on the gels, has demonstrated that "slow" cells reveal an increased basal level of EGF-receptor tyrosine kinase (TK) activity compared to the "fast" cells. Pretreatment of "fast" cells with Mn2+, which was shown to induce TK stimulation without EGF (Mohammadi [correction of Muhammedi et al., 1993), caused a dramatic decrease in 125I-EGF transition to heavy endosomes and lysosomes. Analysis of tyrosine phosphorylation of the receptor, being performed in Mn(2+)-pretreated A431 cells, has confirmed the significant increase of 32P-incorporation into unoccupied EGFR. Taken together, our data suggest that sorting of internalized EGF-receptor complexes depends on the basal TK activity level of EGFR.
authors.forename: K O
authors.initials: KO
authors.lastname: Avrov
authors.forename: A D
authors.initials: AD
authors.lastname: Blagoveshchenskaia
authors.forename: E S
authors.initials: ES
authors.lastname: Kornilova
authors.forename: N N
authors.initials: NN
authors.lastname: Nikol'skiĭ
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell; D002451:Cell Compartmentation / Q000502:physiology; D004705:Endocytosis / Q000502:physiology*; D004815:Epidermal Growth Factor / Q000302:isolation & purification / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D051379:Mice; D015388:Organelles / Q000201:enzymology; D010766:Phosphorylation; D014407:Tumor Cells, Cultured
chemical_list: D007457:Iodine Radioisotopes; D004815:Epidermal Growth Factor; D066246:ErbB Receptors
vernacular_title: Zavisimost' tipa éndotsitoza EFR-retseptornykh kompleksov ot bazal'nogo urovnia aktivnosti tirozinkinazy retseptora épidemal'nogo faktora rosta.