-Catenin N- and C-terminal Tails Modulate the Coordinated Binding of Adherens Junction Proteins to -Catenin* Received for publication, May 6, 2002, and in revised form, June 17, 2002 Published, JBC Papers in Press, June 20, 2002, DOI 10.1074/jbc.M204376200 Julio Castan ˜ o‡§, Imma Raurell‡¶, Jose ´ A. Piedra‡¶, Susana Miravet‡, Mireia Dun ˜ ach‡**, and Antonio Garcı ´a de Herreros¶‡‡ From the ‡Unitat de Biofı´sica, Departament de Bioquı´mica i Biologia Molecular, Facultat de Medicina, Universitat Auto `noma de Barcelona, 08193 Bellaterra, Spain and ¶Unitat de Biologia Cellular i Molecular, Institut Municipal d’Investigacio ´ Me `dica, Universitat Pompeu Fabra, 08003 Barcelona, Spain -Catenin plays a central role in the establishment and regulation of adherens junctions because it interacts with E-cadherin and, through -catenin, with the actin cy- toskeleton. -Catenin is composed of three domains: a central armadillo repeat domain and two N- and C- terminal tails. The C-tail interacts with the armadillo do- main and limits its ability to bind E-cadherin and other cofactors. The two -catenin tails are mutually inter- regulated because the C-tail is also necessary for binding of the N-tail to the armadillo domain. Moreover, the N-tail restricts the interaction of the C-tail with the central do- main. Depletion of either of the two tails has conse- quences for the binding of factors at the other end: dele- tion of the C-tail increases -catenin binding, whereas deletion of the N-tail blocks E-cadherin interaction to the armadillo repeats. As an effect of the interconnection of the tails, the association of -catenin and E-cadherin to -catenin is interdependent. Thus, binding of -catenin to the N-tail, through conformational changes that affect the C-tail, facilitates the association of E-cadherin. These re- sults indicate that different cofactors of -catenin bind coordinately to this protein and indicate how the two terminal ends of -catenin exquisitely modulate intermo- lecular binding within junctional complexes. -Catenin is a multifunctional protein that exerts two essen- tial functions in epithelial cells. It is necessary for the mainte- nance of adherens junctions because it binds E-cadherin and connects it, through -catenin, to the actin cytoskeleton (1, 2). On the other hand, when not bound to E-cadherin, -catenin can move to the nucleus and act as a transcriptional co-activator, through the interaction with members of the T cell transcription factor family (3). In addition to T cell transcription factor pro- teins, several other transcriptional factors have been reported to interact with -catenin, presumably modulating its positive ac- tivity on the transcription of several target genes (4). On the other hand, a complex of proteins containing the product of the adenomatous polyposis coli, axin, glycogen synthase kinase 3, and -TrCP/slimb is involved in the targeting of cytosolic -cate- nin to the proteasome and subsequent degradation, therefore precluding its transport to the nucleus and its transcriptional activity (4). It is widely accepted that tyrosine modification of -catenin regulates formation or disassembly of adherens junctions. Data from different groups have indicated a relationship between ad- herens junction disruption and tyrosine phosphorylation of -catenin (reviewed in Ref. 5), although some discrepant data have also been reported (5, 6). By using recombinant proteins, our group has demonstrated that phosphorylation of a specific -catenin tyrosine residue, Tyr-654, decreases its interaction with E-cadherin (7). Experiments in which transfections of -catenin Tyr-654 mutants in different cell lines were performed further support the relevance of the phosphorylation of this ty- rosine residue (7, 8). Additional evidence has been provided by the elucidation of the crystal structure of the complex formed by the -catenin-E-cadherin binding domains; -catenin Tyr-654 is one of the key residues involved in the stabilization of this com- plex through the interaction with E-cadherin Asp-665 (9). -Catenin can be divided in three different sub-domains. The central domain is composed of 12 repetitions of 42 amino acids each, which have been named armadillo repeats, after the -catenin ortholog in Drosophila, armadillo. This region, with a basic pI, has been crystallized; it forms a very rigid structure, a super helix composed by 36 small -helices (3 per each arma- dillo repeat) (10). Tyr-654 lies on the last repeat of this domain. However, the structure of the entire protein with the two -catenin terminal domains, the N- and the C-tails, is still unknown. Contrary to the armadillo repeat domain, these ter- minal tails are mainly acidic (in both the pI is 4.5), and their degree of conservation among different species is much lower than the central core. Recently, we have described (11) that -catenin C-tail interacts with the armadillo domain and that this interaction is controlled by Tyr-654 phosphorylation. This association limits the ability of -catenin to bind E-cadherin and other cofactors involved in its transcriptional activity, such as the TATA-binding protein (TBP) 1 (11). We describe here that * This work was supported in part by Grants 01/045-00 from Fun- dacio ´ La Caixa (to A. G. H.), PM-99-0132 and PM99-0064 from Minis- terio de Ciencia y Tecnologı ´a (to A. G. H. and M. D., respectively), 2FD97-1491-C02-01 and 2FD97-1491-C02-02 from FEDER-Fondo Na- cional I+D Funds (to A. G. H. and M. D., respectively), and 2001SGR00410 and 2001SGR00197 from Direccio ´ General de Recerca. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact. § Recipient of a predoctoral fellowship awarded by Ministerio de Educacio ´n y Ciencia.  Recipient of a predoctoral fellowship awarded by CIRIT (Generalitat de Catalunya). ** To whom correspondence may be addressed: Unitat de Biofı ´sica, Dept. Bioquı ´mica i Biologia Molecular, Facultat de Medicina, Univer- sitat Auto `noma de Barcelona, 08193 Bellaterra, Spain. Tel.: 34-93-581- 1870; Fax: 34-93-581-1907; E-mail: mireia.dunach@uab.es. ‡‡ To whom correspondence may be addressed: Institut Municipal d’Investigacio ´ Me `dica, c/o Dr. Aiguader 80, 08003 Barcelona, Spain. Tel.: 34-93-221-1009; Fax: 34-93-221-3237; E-mail: agarcia@imim.es. 1 The abbreviations used are: TBP, TATA-binding protein; arm, -catenin armadillo domain; GST, glutathione S-transferase; cytoE- cadh, cytosolic domain of E-cadherin; mAb, monoclonal antibody; Tyr(P), phosphotyrosine; N-tail, N-terminal tail; C-tail, C-terminal tail. THE JOURNAL OF BIOLOGICAL CHEMISTRY Vol. 277, No. 35, Issue of August 30, pp. 31541–31550, 2002 © 2002 by The American Society for Biochemistry and Molecular Biology, Inc. Printed in U.S.A. This paper is available on line at http://www.jbc.org 31541