GBP binds kinesin light chain and translocates during cortical rotation in Xenopus eggs.
In Xenopus, axis development is initiated by dorsally elevated levels of cytoplasmic beta-catenin, an intracellular factor regulated by GSK3 kinase activity. Upon fertilization, factors that increase beta-catenin stability are translocated to the prospective dorsal side of the embryo in a microtubule-dependent process. However, neither the identity of these factors nor the mechanism of their movement is understood. Here, we show that the GSK3 inhibitory protein GBP/Frat binds kinesin light chain (KLC), a component of the microtubule motor kinesin. Upon egg activation, GBP-GFP and KLC-GFP form particles and exhibit directed translocation. KLC, through a previously uncharacterized conserved domain, binds a region of GBP that is required for GBP translocation and for GSK3 binding, and competes with GSK3 for GBP. We propose a model in which conventional kinesin transports a GBP-containing complex to the future dorsal side, where GBP dissociates and contributes to the local stabilization of beta-catenin by binding and inhibiting GSK3.
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D000072261:Dishevelled Proteins; D017930:Genes, Reporter; D047908:Intracellular Signaling Peptides and Proteins; D016547:Kinesins; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010063:Ovum / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D000072261:Dishevelled Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008869:Microtubule-Associated Proteins; C112892:PIAS1 protein, Xenopus; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D029867:Xenopus Proteins; D016547:Kinesins