PT - JOURNAL ARTICLE AU - Zhangguo Chen AU - Rémi Gaudreau AU - Christian Le Gouill AU - Marek Rola-Pleszczynski AU - Jana Staňková TI - Agonist-Induced Internalization of Leukotriene B<sub>4</sub> Receptor 1 Requires G-Protein-Coupled Receptor Kinase 2 but Not Arrestins DP - 2004 Sep 01 TA - Molecular Pharmacology PG - 377--386 VI - 66 IP - 3 4099 - http://molpharm.aspetjournals.org/content/66/3/377.short 4100 - http://molpharm.aspetjournals.org/content/66/3/377.full SO - Mol Pharmacol2004 Sep 01; 66 AB - The leukotriene B4 (LTB4) receptor (BLT1) becomes desensitized upon repeated agonist stimulation. Little is known, however, about BLT1 internalization, which follows desensitization in most G-protein-coupled receptors (GPCR). In the current study, transiently expressed BLT1 readily internalized, after LTB4 stimulation, in RBL-2H3 cells that express high levels of endogenous GPCR kinase 2 (GRK2) but did not in COS-7 or human embryonic kidney (HEK) 293 cells, which do not overexpress GRK. The internalization of BLT1 could be blocked in RBL-2H3 cells by coexpressing dominant-negative (DN) GRK2 K220R and could be promoted in HEK293 cells by coexpressing wild-type (WT) GRK2. Coexpression of WT or DN nonvisual arrestins had no effect on BLT1 internalization. Moreover, upon stimulation with LTB4, BLT1 did not induce arrestin-green fluorescence protein redistribution in either cell type, even in the presence of overexpressed GRK2. Coimmunoprecipitation experiments confirmed that BLT1 could associate with GRK2 but not with arrestins. A C-tail–truncated mutant of BLT1 lost the capacity to internalize and associate with GRK2 upon exposure to LTB4, suggesting that the C-tail was required for receptor internalization and association with GRK2. Taken together, our results indicate that the C terminus of BLT1 plays a pivotal role in receptor internalization and GRK2 association. Moreover, ligand-induced BLT1 internalization is dependent on GRK2 but independent of arrestins. This may allow differential, cell-type–specific signaling in response to LTB4, depending on GRK expression levels.