Understanding the biological functions of POPX2 phosphatase through its interactome

Abstract

POPX2 (Partner of PIX 2) is a serine/threonine phosphatase known to dephosphorylate PAK1, CaMKII and TAK1. POPX2 has been reported to be positively associated with cell motility and invasiveness of breast cancer cells. In order to further investigate the roles and functions of POPX2 in the cells, we have adopted two approaches to identify POPX2-interacting proteins. In the first approach, we pulled down Flag-tagged POPX2 and determined the co-precipitated proteins using mass spectrometry (MS). We discovered Coronin 1C (Coro 1C) as a potential POPX2-interacting protein. In the second approach, we used a combination of SILAC-MS proteomics and bioinformatic analysis and identified Check point kinase 1 (Chk1) as a binding partner and possible substrate of POPX2.