All ErbB Receptors Other Than the Epidermal Growth Factor Receptor Are Endocytosis Impaired

doi:10.1074/jbc.271.9.5251

All ErbB Receptors Other Than the Epidermal Growth Factor Receptor Are Endocytosis Impaired (*)

From the (1)Departments of Biochemistry and
(2)Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0146 and the
(3)Laboratory of Cellular and Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892

^¶ To whom correspondence should be addressed:
Dept. of Biochemistry, Rm. 647, Light Hall, Vanderbilt University School of Medicine, Nashville, TN 37232-0146.
Tel.: 615-322-6678; Fax: 615-322-2931.

↵^§ Present address: Dept. of Experimental Oncology, European Institute of Oncology, Milano, Italy.

Abstract

Four transmembrane tyrosine kinases constitute the ErbB receptor family: the epidermal growth factor (EGF) receptor, ErbB-2, ErbB-3, and ErbB-4. We have measured the endocytic capacities of all four members of the EGF receptor family, including ErbB-3 and ErbB-4, which have not been described previously. EGF-responsive chimeric receptors containing the EGF receptor extracellular domain and different ErbB cytoplasmic domains (EGFR/ErbB) have been employed. The capacity of these growth factor-receptor complexes to mediate I-EGF internalization, receptor down-regulation, receptor degradation, and receptor co-immunoprecipitation with AP-2 was assayed. In contrast to the EGF receptor, all EGFR/ErbB receptors show impaired ligand-induced rapid internalization, down-regulation, degradation, and AP-2 association. Also, we have analyzed the heregulin-responsive wild-type ErbB-4 receptor, which does not mediate the rapid internalization of I-heregulin, demonstrates no heregulin-regulated receptor degradation, and fails to form association complexes with AP-2. Despite the substantial differences in ligand-induced receptor trafficking between the EGF and ErbB-4 receptors, EGF and heregulin have equivalent capacities to stimulate DNA synthesis in quiescent cells. These results show that the ligand-dependent down-regulation mechanism of the EGF receptor, surprisingly, is not a property of any other known ErbB receptor family member. Since endocytosis is thought to be an attenuation mechanism for growth factor-receptor complexes, these data imply that substantial differences in attenuation mechanisms exist within one family of structurally related receptors.

Footnotes

↵* This work was supported by National Institutes of Health Grant CA24071 and a fellowship from the Spanish Ministerio de Educacion y Ciencia. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

EGF

epidermal growth factor

EGFR

EGF receptor

DMEM

Dulbecco's modified Eagle's medium

AP-2

plasma membrane clathrin-associated protein complex

PBS

phosphate-buffered saline

GST

glutathione S-transferase

PCR

polymerase chain reaction.
- Received September 15, 1995.
- Revision received November 30, 1995.