PT  - JOURNAL ARTICLE
AU  - Qi Xu
AU  - Ning Xu
AU  - Tan Zhang
AU  - Hui Zhang
AU  - Zijian Li
AU  - Feng Yin
AU  - Zhizhen Lu
AU  - Qide Han
AU  - Youyi Zhang
TI  - Mammalian Tolloid Alters Subcellular Localization, Internalization, and Signaling of α<sub>1a</sub>-Adrenergic Receptors
AID  - 10.1124/mol.105.016451
DP  - 2006 Aug 01
TA  - Molecular Pharmacology
PG  - 532--541
VI  - 70
IP  - 2
4099  - http://molpharm.aspetjournals.org/content/70/2/532.short
4100  - http://molpharm.aspetjournals.org/content/70/2/532.full
SO  - Mol Pharmacol2006 Aug 01; 70
AB  - In the present study, we identified the CUB5 domain of mammalian Tolloid (mTLD) as a novel protein binding to α1A-adrenergic receptor (AR) using the yeast two-hybrid system. Whereas CUB5 did not couple to either α1B-AR or α1D-AR. It was determined that amino acids 322 to 359 of α1A-AR were the major binding region for CUB5. The direct interaction between α1A-AR cytoplasmic tail and CUB5 was discovered by glutathione S-transferase pull-down assay. We confirmed the interaction of mTLD with α1A-AR in human embryonic kidney (HEK) 293 cells by immunoprecipitation, immunofluorescence, and fluorescence resonance energy transfer. Although mTLD did not affect the density and affinity of receptors in crudely prepared membranes from HEK293 cells stably expressing α1A-AR, it significantly altered the subcellular localization of the receptors. Moreover, mTLD reduced the level of cell surface α1A-ARs, delayed the initial rate of agonist-induced receptor internalization, and facilitated agonist-induced calcium transient. We have demonstrated that mTLD interacts with α1A-AR directly, alters the subcellular localization of receptor, and influences agonist-induced α1A-AR internalization and calcium signaling.