ATF-7, a Novel bZIP Protein, Interacts with the PRL-1 Protein-tyrosine Phosphatase

Charles S Peters,Xianping Liang,Shuixing Li,Subburaj Kannan,Yong Peng,Rebecca Taub,Robert H Diamond

doi:10.1074/jbc.m011562200

Charles S Peters, Xianping Liang + Show 5 more

Open Access

https://doi.org/10.1074/jbc.m011562200

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Abstract

We have identified a novel basic leucine zipper (bZIP) protein, designated ATF-7, that physically interacts with the PRL-1 protein-tyrosine phosphatase (PTPase). PRL-1 is a predominantly nuclear, farnesylated PTPase that has been linked to the control of cellular growth and differentiation. This interaction was initially found using the yeast two-hybrid system. ATF-7 is most closely related to members of the ATF/CREB family of bZIP proteins, with highest homology to ATF-4. ATF-7 homodimers can bind specifically to CRE elements. ATF-7 is expressed in a number of different tissues and is expressed in association with differentiation in the Caco-2 cell model of intestinal differentiation. We have confirmed the PRL-1.ATF-7 interaction and mapped the regions of ATF-7 and PRL-1 important for interaction to ATF-7's bZIP region and PRL-1's phosphatase domain. Finally, we have determined that PRL-1 is able to dephosphorylate ATF-7 in vitro. Further insight into ATF-7's precise cellular roles, transcriptional function, and downstream targets are likely be of importance in understanding the mechanisms underlying the complex processes of maintenance, differentiation, and turnover of epithelial tissues.

Highlights

It is clear that many cellular processes are regulated through protein phosphorylation
We have identified a novel basic leucine zipper protein, designated ATF-7, that physically interacts with the PRL-1 protein-tyrosine phosphatase (PTPase)
We have functionally confirmed that ATF-7 is a basic leucine zipper (bZIP) protein by showing that its homodimers bind to cyclic AMP response (CRE) elements

Summary

Introduction

It is clear that many cellular processes are regulated through protein phosphorylation. We have identified a novel basic leucine zipper (bZIP) protein, designated ATF-7, that physically interacts with the PRL-1 protein-tyrosine phosphatase (PTPase). We used electromobility shift assays to test the ability of in vitro translated ATF-7 to bind different DNA sequences known to bound by bZIP proteins.

Results

Conclusion