Binding with heat shock cognate protein HSC70 fine-tunes the Golgi association of the small GTPase ARL5B |
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Authors: | Ebsy Jaimon Aashutosh Tripathi Arohi Khurana Dipanjana Ghosh Jini Sugatha Sunando Datta |
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Institution: | Department of Biological Sciences, Indian Institute of Science Education and Research Bhopal, Bhopal, India |
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Abstract: | ARL5B, an ARF-like small GTPase localized to the trans-Golgi, is known for regulating endosome-Golgi trafficking and promoting the migration and invasion of breast cancer cells. Although a few interacting partners have been identified, the mechanism of the shuttling of ARL5B between the Golgi membrane and the cytosol is still obscure. Here, using GFP-binding protein (GBP) pull-down followed by mass spectrometry, we identified heat shock cognate protein (HSC70) as an additional interacting partner of ARL5B. Our pull-down and isothermal titration calorimetry (ITC)-based studies suggested that HSC70 binds to ARL5B in an ADP-dependent manner. Additionally, we showed that the N-terminal helix and the nucleotide status of ARL5B contribute to its recognition by HSC70. The confocal microscopy and cell fractionation studies in MDA-MB-231 breast cancer cells revealed that the depletion of HSC70 reduces the localization of ARL5B to the Golgi. Using in vitro reconstitution approach, we provide evidence that HSC70 fine-tunes the association of ARL5B with Golgi membrane. Finally, we demonstrated that the interaction between ARL5B and HSC70 is important for the localization of cation independent mannose-6-phosphate receptor (CIMPR) at Golgi. Collectively, we propose a mechanism by which HSC70, a constitutively expressed chaperone, modulates the Golgi association of ARL5B, which in turn has implications for the Golgi-associated functions of this GTPase. |
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Keywords: | small GTPase ARF-like proteins chaperone Golgi protein myristoylation membrane reconstitution |
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