Characterization of the Interaction of FKBP12 with the Transforming Growth Factor-β Type I Receptor in Vivo

doi:10.1074/jbc.271.36.21687

Characterization of the Interaction of FKBP12 with the Transforming Growth Factor-β Type I Receptor *in Vivo**

From the ^‡ Department of Biochemistry, The Cancer Institute, Tokyo, Japanese Foundation for Cancer Research, 1-37-1 Kami-Ikebukuro, Toshima-ku, Tokyo 170, Japan and
^§ The Vanderbilt Cancer Center, Nashville, Tennessee 37232

^∥ To whom correspondence should be addressed. Tel.: 81-3-5394-3866; Fax: 81-3-3918-0342; E-mail: mkawabat-ind{at}umin.u-tokyo.ac.jp.

Abstract

The type I transforming growth factor-β receptor (TβR-I) is the efferent component of the receptor complex, which presumably phosphorylates intracellular targets. FKBP12, a binding protein for FK506 and rapamycin, is shown to associate with the cytoplasmic region of TβR-I in vitro. In this report, we investigated the interaction of FKBP12 with TβR-I in vivo. FKBP12 interacts with TβR-I in mammalian cells as well as in yeast. Ligand addition does not affect the interaction, and both constitutively active and kinase-negative mutants of TβR-I bind FKBP12. FKBP12 dissociates from TβR-I in the presence of a high concentration of FK506. The juxtamembrane region of TβR-I, containing the major phosphorylation sites by the type II receptor, is required for the interaction. One of the deletion mutants in this region, which was shown to mediate transcriptional response, does not bind FKBP12, suggesting that FKBP12 is not directly involved in TGF-β signaling. Furthermore TβR-I does not phosphorylate FKBP12 in vitro. FKBP12 may not be a direct substrate of TβR-I but possibly modulates the TβR-I function through its interaction with the regulatory domain of the kinase.

Footnotes

↵^¶ Supported by Haraguchi Memorial Cancer Research Fund, Uehara Memorial Foundation, and Mochida Memorial Foundation for Medical and Pharmaceutical Research.
↵* This work was supported by grants-in-aid for scientific research from the Ministry of Education, Science and Culture of Japan. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

TGF-β

transforming growth factor-β

BMP

bone morphogenetic protein

TβR

TGF-β

receptor

GS domain

glycine-serine-rich domain

FTα

farnesyl transferase-α

PCR

polymerase chain reaction

GST

glutathione S-transferase

HA

hemagglutinin

PAGE

polyacrylamide gel electrophoresis

RyR

ryanodine receptor.
- Received July 2, 1996.