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KMID : 0624620120450060360
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BMB Reports
2012 Volume.45 No. 6 p.360 ~ p.364
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Affinity between TBC1D4 (AS160) phosphotyrosine-binding domain and insulin-regulated aminopeptidase cytoplasmic domain measured by isothermal titration calorimetry
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Park Sang-Youn
Kim Keon-Young
Kim Sun-Min
Yu Young-Seok
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Abstract
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Uptake of circulating glucose into the cells happens via the insulin- mediated signalling pathway, which translocates the glucose transporter 4 (GLUT4) vesicles from the intracellular compartment to the plasma membrane. RabㆍGTPases are involved in this vesicle trafficking, where RabㆍGTPase-activating proteins (RabGAP) enhance the GTP to GDP hydrolysis. TBC1D4 (AS160) and TBC1D1 are functional RabGAPs in the adipocytes and the skeletonal myocytes, respectively. These proteins contain two phosphotyrosine-binding domains (PTBs) at the amino-terminus of the catalytic RabGAP domain. The second PTB has been shown to interact with the cytoplasmic region of the insulin-regulated aminopeptidase (IRAP) of the GLUT4 vesicle. In this study, we quantitatively measured the ∼μM affinity (KD) between TBC1D4 PTB and IRAP using isothermal titration calorimetry, and further showed that IRAP residues 1-49 are the major region mediating this interaction. We also demonstrated that the IRAP residues 1-15 are necessary but not sufficient for the PTB interaction.
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KEYWORD
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IRAP, Isothermal titration calorimetry, Protein-protein interaction, PTB domain, TBC1D4 (AS160)
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