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Intraflagellar transport-A complex mediates ciliary entry and retrograde trafficking of ciliary G protein–coupled receptors
Cilia serve as cellular antennae where proteins involved in sensory and developmental signaling, including G protein–coupled receptors (GPCRs), are specifically localized. Intraflagellar transport (IFT)-A and -B complexes mediate retrograde and anterograde ciliary protein trafficking, respectively....
Autores principales: | , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The American Society for Cell Biology
2017
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5341726/ https://www.ncbi.nlm.nih.gov/pubmed/27932497 http://dx.doi.org/10.1091/mbc.E16-11-0813 |
Sumario: | Cilia serve as cellular antennae where proteins involved in sensory and developmental signaling, including G protein–coupled receptors (GPCRs), are specifically localized. Intraflagellar transport (IFT)-A and -B complexes mediate retrograde and anterograde ciliary protein trafficking, respectively. Using a visible immunoprecipitation assay to detect protein–protein interactions, we show that the IFT-A complex is divided into a core subcomplex, composed of IFT122/IFT140/IFT144, which is associated with TULP3, and a peripheral subcomplex, composed of IFT43/IFT121/IFT139, where IFT139 is most distally located. IFT139-knockout (KO) and IFT144-KO cells demonstrated distinct phenotypes: IFT139-KO cells showed the accumulation of IFT-A, IFT-B, and GPCRs, including Smoothened and GPR161, at the bulged ciliary tips; IFT144-KO cells showed failed ciliary entry of IFT-A and GPCRs and IFT-B accumulation at the bulged tips. These observations demonstrate the distinct roles of the core and peripheral IFT-A subunits: IFT139 is dispensable for IFT-A assembly but essential for retrograde trafficking of IFT-A, IFT-B, and GPCRs; in contrast, IFT144 is essential for functional IFT-A assembly and ciliary entry of GPCRs but dispensable for anterograde IFT-B trafficking. Thus the data presented here demonstrate that the IFT-A complex mediates not only retrograde trafficking but also entry into cilia of GPCRs. |
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