PDBsum entry 2k1z

Signaling protein

PDB id: 2k1z

Contents

Protein chain

104 a.a. *

* Residue conservation analysis

PDB id:

2k1z

Name:

Signaling protein

Title:

Solution structure of par-3 pdz3

Structure:

Partitioning-defective 3 homolog. Chain: a. Fragment: pdz 3 domain. Synonym: pard-3, par-3, atypical pkc isotype-specific-interacting protein, asip, atypical pkc-specific-binding protein, asbp. Engineered: yes

Source:

Rattus norvegicus. Rat. Gene: pard3, par3. Expressed in: escherichia coli.

NMR struc:

20 models

Authors:

W.Feng,H.Wu,L.Chan,M.Zhang

Key ref:

W.Feng et al. (2008). Par-3-mediated junctional localization of the lipid phosphatase PTEN is required for cell polarity establishment. J Biol Chem, 283, 23440-23449. PubMed id: 18550519 DOI: 10.1074/jbc.M802482200

Date:

18-Mar-08 Release date: 10-Jun-08

Protein chain

Q9Z340  (PARD3_RAT) -  Partitioning defective 3 homolog from Rattus norvegicus

Seq: 1337 a.a.

Struc: 104 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1074/jbc.M802482200

J Biol Chem 283:23440-23449 (2008)

PubMed id: 18550519

Par-3-mediated junctional localization of the lipid phosphatase PTEN is required for cell polarity establishment.

W.Feng, H.Wu, L.N.Chan, M.Zhang.

ABSTRACT

PDZ domain-containing scaffold protein Par-3 is the central organizer of the evolutionarily conserved cell polarity-regulatory Par-3.Par-6.atypical protein kinase C complex. The PDZ domains of Par-3 have also been implicated as potential phosphoinositide signaling integrators, since its second PDZ domain binds to phosphoinositides, and the third PDZ interacts with phosphoinositide phosphatase PTEN. However, the molecular basis of Par-3/PTEN interaction is still poorly understood. Additionally, it is not known whether the regulatory function of PTEN in cell polarity is specifically mediated by its interaction with Par-3. The structures of Par-3 PDZ3 in both its free and PTEN tail peptide-bound forms determined in this work reveal that Par-3 PDZ3 binds to PTEN with two discrete binding sites: a canonical PDZ-ligand interaction site and a distal, opposite charge-charge interaction site. This distinct target recognition mechanism confers the interaction specificity of the Par-3.PTEN complex. We show that the Par-3 PDZ3-PTEN binding is required for the enrichment of PTEN at the junctional membranes of Madin-Darby canine kidney cells. Finally, we demonstrate that the junctional membrane-localized PTEN is specifically required for the polarization of Madin-Darby canine kidney cells. These results, together with earlier data, firmly establish that Par-3 functions as a scaffold in integrating phosphoinositide signaling events during cellular polarization.

Selected figure(s)

Figure 1.
Solution structure of Par-3 PDZ3. A, stereoview showing the backbones of 20 superimposed NMR-derived structures of Par-3 PDZ3. B, ribbon diagram of a representative NMR structure of the Par-3 PDZ3. The secondary structure elements of PDZ3 are labeled according to the scheme used for the canonic PDZ domains. The potential peptide binding pocket is highlighted by a magenta oval. C, amino acid sequence alignment of the Par-3 PDZ3 from different species. The highly conserved hydrophobic, positively charged, and negatively charged residues are in yellow, blue, and red, respectively; other highly conserved residues are in green. The secondary structures of Par-3 PDZ3 and the residue number are marked at the top of the alignment. The positively charged residues responsible for the specific charge-charge interaction between PDZ3 and the PTEN peptide are highlighted by blue triangles. The protein structure figures were prepared using the programs MOLMOL (45), MOLSCRIPT (46), PyMOL (available on the World Wide Web), and GRASP (47).

Figure 4.
Par-3 enriches PTEN at the junctional membranes via its PDZ3 domain. A, overexpressed Par-3 was specifically enriched at the junctional membrane in polarized epithelial cells, and PTEN was partially colocalized with Par-3 (white arrows). In this experiment, MDCK II cells were transiently co-transfected with GFP-Par-3 and Myc-PTEN. B, C-terminal tail deletion mutant of PTEN failed to colocalize with Par-3 at the junctional membrane regions (arrowhead). C, the DED3A mutant of PTEN also failed to colocalize with Par-3 at the membrane junctions (arrowhead). Instead, the PTEN mutant is diffused in the cytoplasm. D, PDZ2 lipid binding-deficient mutant of Par-3 (K3E) is diffused in cytoplasm (25). Co-expressed PTEN is also absent at the junctional membranes. E, the oligomerization-deficient mutant of Par-3 (ΔNTD) (21) is diffused in MDCK cells. Co-expressed PTEN is also missing from the junctional membranes. Note that the Par-3 mutants in D and E retain the PTEN binding capacities. Scale bar, 10 μm. WT, wild type.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2008, 283, 23440-23449) copyright 2008.

Figures were selected by an automated process.