Affinity between TBC1D4 (AS160) phosphotyrosine-binding domain and insulin-regulated aminopeptidase cytoplasmic domain measured by isothermal titration calorimetry.
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.
School of Systems Biomedical Science, Soongsil University, Seoul 156-743, Korea psy@ssu.ac.kr.
SangYoun
S
Park
Keon Young
KY
Kim
Sunmin
S
Kim
Young Seok
YS
Yu
D002151:Calorimetry; D010122:Cystinyl Aminopeptidase / Q000737:chemistry / Q000378:metabolism; D020690:GTPase-Activating Proteins / Q000737:chemistry / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction
D020690:GTPase-Activating Proteins; D051275:Glucose Transporter Type 4; D007328:Insulin; C518767:TBC1D4 protein, human; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase