Drosophila α-Catenin and E-cadherin Bind to Distinct Regions of Drosophila Armadillo

doi:10.1074/jbc.271.50.32411

Drosophila α-Catenin and E-cadherin Bind to Distinct Regions of Drosophila Armadillo*

From the Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280 and the
^∥ Department of Biophysics, Kyoto University, Kyoto 606-01, Japan

^″ To whom correspondence should be addressed.

↵^¶ Contributed equally to this work.

Abstract

Adherens junctions are multiprotein complexes mediating cell-cell adhesion and communication. They are organized around a transmembrane cadherin, which binds a set of cytoplasmic proteins required for adhesion and to link the complex to the actin cytoskeleton. Three components of Drosophila adherens junctions, analogous to those in vertebrates, have been identified: Armadillo (homolog of β-catenin), Drosophila E-cadherin (DE-cadherin), and α-catenin. We carried out the first analysis of the interactions between these proteins using in vitro binding assays, the yeast two-hybrid system, and in vivo assays. We identified a 76-amino acid region of Armadillo that is necessary and sufficient for binding α-catenin and found that the N-terminal 258 amino acids of α-catenin interact with Armadillo. A large region of Armadillo, spanning six central Armadillo repeats, is required for DE-cadherin binding, whereas only 41 amino acids of the DE-cadherin cytoplasmic tail are sufficient for Armadillo binding. Our data complement and extend results obtained in studies of vertebrate adherens junctions, providing a foundation for understanding how junctional proteins assemble and a basis for interpreting existing mutations and creating new ones.

Footnotes

↵* This work was supported by a grant from the March of Dimes and Grant GM47857 from the National Institutes of Health (to M. P.). 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:

Arm

Armadillo

DE-cadherin

Drosophila E-cadherin

GST

glutathione S-transferase

PCR

polymerase chain reaction

RIPA

radioimmune precipitation assay

PAGE

polyacrylamide gel electrophoresis

ConA

concanavalin A

APC

adenomatous polyposis coli.
- Received June 6, 1996.
- Revision received September 30, 1996.