The carboxyl terminus of epidermal growth factor receptor/erbB-2 chimerae is internalization impaired.
The endocytosis of gp185erbB-2 was studied using chimeric receptors in which the intracellular domain of erbB-2, or subdomins thereof, was substituted for the corresponding regions of the epidermal growth factor (EGF) receptor. Chimeric and wild-type EGF or erbB-2 receptors were expressed in mouse NIH3T3 or NR6 fibroblasts and in a human mammary adenocarcinoma cell line, MDAMB-134. The rate of EGF-induced internalization for the chimera consisting of the extracellular EGF receptor domain and intracellular erbB-2 domain was reduced three- to fourfold compared with the wild-type EGF receptor. The low rate of internalization of the chimeric receptor resulted in impaired down-regulation and degradation of the receptor. Substitution of the carboxyl terminus of erbB-2 for the corresponding region of the EGF receptor caused a similar decrease of receptor endocytosis, whereas substitution of the erbB-2 tyrosine kinase domain did not affect internalization and down-regulation. Since the tyrosine kinase of the internalization-defective chimeric receptors could be activated by EGF, kinase activity and autophosphorylation of erbB-2 do not appear to be sufficient for a maximum rapid internalization of the chimeric receptors. These results suggest that the carboxyl terminus of erbB-2 either does not possess all the signals required for the rapid internalization or contains an inhibitory signal for rapid internalization.
Sorkin
A
A
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Di Fiore
P P
PP
Carpenter
G
G
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D004815:Epidermal Growth Factor / Q000378:metabolism / Q000494:pharmacology; D066246:ErbB Receptors / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins / Q000378:metabolism*
D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D011518:Proto-Oncogene Proteins; D018719:Erb-b2 Receptor Tyrosine Kinases; D011993:Recombinant Fusion Proteins