Role of binding of plectin to the integrin beta4 subunit in the assembly of hemidesmosomes

We have previously shown that plectin is recruited into hemidesmosomes through association of its actin-binding domain (ABD) with the first pair of fibronectin type III (FNIII) repeats and a small part of the connecting segment (residues 1328-1355) of the integrin beta4 subunit. Here, we show that t...

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Bibliographic Details
Published in:Molecular biology of the cell 2004-03, Vol.15 (3), p.1211-1223
Main Authors: Koster, J, van Wilpe, S, Kuikman, I, Litjens, S H M, Sonnenberg, A
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Binding Sites
Cells, Cultured
Cercopithecus aethiops
Cloning, Molecular
COS Cells
Hemidesmosomes - metabolism
Humans
Integrin beta4 - metabolism
Intermediate Filament Proteins - metabolism
Keratinocytes - metabolism
Keratins - metabolism
Molecular Sequence Data
Plectin
Proline - chemistry
Protein Binding
Protein Structure, Tertiary
Two-Hybrid System Techniques
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Summary:We have previously shown that plectin is recruited into hemidesmosomes through association of its actin-binding domain (ABD) with the first pair of fibronectin type III (FNIII) repeats and a small part of the connecting segment (residues 1328-1355) of the integrin beta4 subunit. Here, we show that two proline residues (P1330 and P1333) in this region of the connecting segment are critical for supporting beta4-mediated recruitment of plectin. Additional binding sites for the plakin domain of plectin on beta4 were identified in biochemical and yeast two-hybrid assays. These sites are located at the end of the connecting segment (residues 1383-1436) and in the region containing the fourth FNIII repeat and the C-tail (residues 1570-1752). However, in cells, these additional binding sites cannot induce the assembly of hemidesmosomes without the interaction of the plectin-ABD with beta4. Because the additional plectin binding sites overlap with sequences that mediate an intramolecular association of the beta4 cytoplasmic domain, we propose that they are not accessible for binding and need to become exposed as the result of the binding of the plectin-ABD to beta4. Furthermore, these additional binding sites might be necessary to position the beta4 cytoplasmic domain for an optimal interaction with other hemidesmosomal components, thereby increasing the efficiency of hemidesmosome assembly.
ISSN:1059-1524