• Register
X
Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

X

Leaving Community

Are you sure you want to leave this community? Leaving the community will revoke any permissions you have been granted in this community.

No
Yes

Ponsin/SH3P12: an l-afadin- and vinculin-binding protein localized at cell-cell and cell-matrix adherens junctions.

We recently isolated a novel actin filament (F-actin)-binding protein, afadin, that has two isoforms, l- and s-afadins. l-Afadin is ubiquitously expressed and specifically localized at zonula adherens (ZA) in epithelial cells and at cell-cell adherens junction (AJ) in nonepithelial cells, whereas s-afadin is abundantly expressed in neural tissue. l-Afadin has one PDZ domain, three proline-rich regions, and one F-actin-binding domain, whereas s-afadin lacks the third proline-rich region and the F-actin-binding domain. To understand the molecular mechanism of the specific localization of l-afadin at ZA in epithelial cells and at cell-cell AJ in nonepithelial cells, we attempted here to identify an l-afadin-binding protein(s) and isolated a protein, named ponsin. Ponsin had many splicing variants and the primary structures of two of them were determined. Both the two variants had three Src homology 3 (SH3) domains and turned out to be splicing variants of SH3P12. The third proline-rich region of l-afadin bound to the region of ponsin containing the second and third SH3 domains. Ponsin was ubiquitously expressed and localized at ZA in epithelial cells, at cell-cell AJ in nonepithelial cells, and at cell-matrix AJ in both types of cells. Ponsin furthermore directly bound vinculin, an F-actin-binding protein localized at ZA in epithelial cells, at cell-cell AJ in nonepithelial cells, and at cell-matrix AJ in both types of cells. Vinculin has one proline-rich region where two proline-rich sequences are located. The proline-rich region bound to the region of ponsin containing the first and second SH3 domains. l-Afadin and vinculin bound to ponsin in a competitive manner and these three proteins hardly formed a ternary complex. These results indicate that ponsin is an l-afadin- and vinculin-binding protein localized at ZA in epithelial cells, at cell-cell AJ in nonepithelial cells, and at cell-matrix AJ in both types of cells.

Pubmed ID: 10085297

Authors

  • Mandai K
  • Nakanishi H
  • Satoh A
  • Takahashi K
  • Satoh K
  • Nishioka H
  • Mizoguchi A
  • Takai Y

Journal

The Journal of cell biology

Publication Data

March 8, 1999

Associated Grants

None

Mesh Terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • COS Cells
  • Cell Membrane
  • DNA, Complementary
  • Kinesin
  • Mice
  • Microfilament Proteins
  • Microscopy, Fluorescence
  • Microscopy, Immunoelectron
  • Molecular Sequence Data
  • Myosins
  • Protein Binding
  • Sequence Homology, Amino Acid
  • Tumor Cells, Cultured
  • Vinculin