Open AccessAffinity between TBC1D4 (AS160) phosphotyrosine-binding domain and insulin-regulated aminopeptidase cytoplasmic domain measured by isothermal titration calorimetry
Author(s) -
SangYoun Park,
Keon Young Kim,
Sunmin Kim,
Young Seok Yu
Publication year - 2012
Publication title -
bmb reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.511
H-Index - 77
eISSN - 1976-670X
pISSN - 1976-6696
DOI - 10.5483/bmbrep.2012.45.6.030
Subject(s) - isothermal titration calorimetry , chemistry , isothermal process , aminopeptidase , insulin , cytoplasm , titration , calorimetry , domain (mathematical analysis) , biophysics , insulin receptor , biochemistry , pleckstrin homology domain , microbiology and biotechnology , materials science , endocrinology , phosphorylation , biology , thermodynamics , insulin resistance , amino acid , leucine , mathematical analysis , physics , mathematics
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.