POPX2 phosphatase regulates the KIF3 kinesin motor complex

• Main Authors: Phang, Hui-Qun, Hoon, Jing-Ling, Lai, Soak-Kuan, Zeng, Yukai, Chiam, Keng-Hwee, Li, Hoi-Yeung, Koh, Cheng-Gee
• Other Authors: School of Biological Sciences
• Format: Article
• Language: English
• Published: 2015
• Subjects: DRNTU::Science::Biological sciences
• Online Access: https://hdl.handle.net/10356/106722; http://hdl.handle.net/10220/25111
• Institution: Nanyang Technological University

The kinesin motors are important in the regulation of cellular functions such as protein trafficking, spindle organization and centrosome separation. In this study, we have identified POPX2, a serine-threonine phosphatase, as an interacting partner of the KAP3 subunit of the kinesin-2 motor. The kinesin-2 motor is a heterotrimeric complex composed of KIF3A, KIF3B motor subunits and KAP3, the non-motor subunit, which binds the cargo. Here we report that the phosphatase POPX2 is a negative regulator of the trafficking of N-cadherin and other cargoes; consequently, it markedly influences cell-cell adhesion. POPX2 affects trafficking by determining the phosphorylation status of KIF3A at serine 690. This is consistent with the observation that the KIF3A-S690A mutant is defective in cargo trafficking. Our studies also implicate CaMKII as the kinase that phosphorylates KIF3A at serine 690. These results strongly suggest that POPX2 and CaMKII are a phosphatase-kinase pair that regulates kinesin-mediated transport and cell-cell adhesion.