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Updated: Aug 19, 2026

PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions
Published on: July 27, 2017
Phosphorylation-dependent binding of 14-3-3 to Par3beta, a human Par3-related cell polarity protein
Tomoko Izaki1, Sachiko Kamakura, Motoyuki Kohjima
1Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Abstract:
Mammalian Par3alpha and Par3beta/Par3L participate in cell polarity establishment and localize to tight junctions of epithelial cells; Par3alpha acts via binding to atypical PKC (aPKC). Here we show that Par3beta as well as Par3alpha interacts with 14-3-3 proteins in a phosphorylation-dependent manner. In the interaction, Ser-746 of Par3beta and the corresponding residue of Par3alpha (Ser-814) likely play a crucial role, since replacement of these residues by unphosphorylatable alanine results in a loss of interacting activity. The mutant Par3 proteins with the replacement are correctly recruited to tight junctions of MDCK cells and to membrane ruffles induced by an active form of the small GTPase Rac in HeLa cells. Thus, the interaction with 14-3-3 appears to be dispensable to Par3 localization. Consistent with this, the Par3alpha-14-3-3 interaction does not inhibit the Par3alpha-aPKC association required for the Par3alpha localization, although the aPKC-binding site lies close to the Ser-814-containing, 14-3-3-interacting region.
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