Single amino acid substitutions in proteins of the armadillo gene family abolish their binding to alpha-catenin.
Analysis of the calcium-dependent cell adhesion molecule E-cadherin has led to the identification of catenins, which are necessary for cadherin function. Growing evidence that cadherins and catenins are subjected to genetic alterations in carcinogenesis makes it especially important to understand protein-protein interactions within the cadherin-catenin complex. Here we report the identification and analysis of the alpha-catenin binding site in plakoglobin (gamma-catenin). Using N- and C-terminal truncations of plakoglobin, we identified a domain of 29 amino acids necessary and sufficient for binding alpha-catenin. The alpha-catenin binding site is fully encoded within exon 3 of plakoglobin but only partially represented in Armadillo repeat 1. This suggests that exons rather than individual Arm repeats encode functional domains of plakoglobin. Site-directed mutagenesis identified residues in the alpha-catenin binding site indispensable for binding in vitro. Analogous mutations in beta-catenin and Armadillo had identical effects. Our results indicate that single amino acid mutations in the alpha-catenin binding site of homologs of Armadillo could prevent a stable association with alpha-catenin, thus affecting cadherin-mediated adhesion.
Aberle
H
H
Max-Planck-Institut für Immunbiologie, Freiburg, Federal Republic of Germany.
Schwartz
H
H
Hoschuetzky
H
H
Kemler
R
R
D000595:Amino Acid Sequence; D000818:Animals; D051186:Armadillo Domain Proteins; D001483:Base Sequence; D001665:Binding Sites; D015820:Cadherins / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002460:Cell Line; D003110:Colonic Neoplasms; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D017931:DNA Primers; D051180:Desmoplakins; D004330:Drosophila; D029721:Drosophila Proteins; D005982:Glutathione Transferase / Q000096:biosynthesis; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D004676:Myelin Basic Protein / Q000096:biosynthesis; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D015183:Restriction Mapping; D017384:Sequence Deletion; D015534:Trans-Activators; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D051178:alpha Catenin; D051185:gamma Catenin
C495305:ARM protein, Drosophila; D051186:Armadillo Domain Proteins; C495273:CTNNA1 protein, human; D015820:Cadherins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D017931:DNA Primers; D051180:Desmoplakins; D029721:Drosophila Proteins; C495292:JUP protein, human; D004676:Myelin Basic Protein; D011506:Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051178:alpha Catenin; D051185:gamma Catenin; D005982:Glutathione Transferase