Related Experiment Video
Updated: Aug 23, 2026

Using In Vitro Fluorescence Resonance Energy Transfer to Study the Dynamics Of Protein Complexes at a Millisecond Time Scale
Published on: March 14, 2019
Nucleotide exchange factor ECT2 interacts with the polarity protein complex Par6/Par3/protein kinase Czeta (PKCzeta)
Xiu-Fen Liu1, Hiroshi Ishida, Razi Raziuddin
1Molecular Tumor Biology Section, Laboratory of Cell Biology, National Cancer Institute, Building 37, Room 2144, 37 Convent Dr., MSC 4255, Bethesda, MD 20892-4255, USA.
Abstract:
Regulation of cell polarity is an important biological event that governs diverse cell functions such as localization of embryonic determinants and establishment of tissue and organ architecture. The Rho family GTPases and the polarity complex Par6/Par3/atypical protein kinase C (PKC) play a key role in the signaling pathway, but the molecules that regulate upstream signaling are still not known. Here we identified the guanine nucleotide exchange factor ECT2 as an activator of the polarity complex. ECT2 interacted with Par6 as well as Par3 and PKCzeta. Coexpression of Par6 and ECT2 efficiently activated Cdc42 in vivo. Overexpression of ECT2 also stimulated the PKCzeta activity, whereas dominant-negative ECT2 inhibited the increase in PKCzeta activity stimulated by Par6. ECT2 localization was detected at sites of cell-cell contact as well as in the nucleus of MDCK cells. The expression and localization of ECT2 were regulated by calcium, which is a critical regulator of cell-cell adhesion. Together, these results suggest that ECT2 regulates the polarity complex Par6/Par3/PKCzeta and possibly plays a role in epithelial cell polarity.
Related Concept Videos
Nuclear Export
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
Regulation of Nuclear Protein Sorting
Cytoskeletal Coordination in Cell Migration
Long-patch Base Excision Repair
Coat Assembly and GTPases
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Protein Complexes with Interchangeable Parts
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...

