title: The carboxy-terminal tail or the intracellular loop 3 is required for β-arrestin-dependent internalization of a mammalian type II GnRH receptor.
abstract: The type II GnRH receptor (GnRH-R2) in contrast to mammalian type I GnRH receptor (GnRH-R1) has a cytosolic carboxy-terminal tail. We investigated the role of β-arrestin 1 in GnRH-R2-mediated signalling and mapped the regions in GnRH-R2 required for recruitment of β-arrestin, employing internalization assays. We show that GnRH-R2 activation of ERK is dependent on β-arrestin and protein kinase C. Appending the tail of GnRH-R2 to GnRH-R1 enabled GRK- and β-arrestin-dependent internalization of the chimaeric receptor. Surprisingly, carboxy-terminally truncated GnRH-R2 retained β-arrestin and GRK-dependent internalization, suggesting that β-arrestin interacts with additional elements of GnRH-R2. Mutating serine and threonine or basic residues of intracellular loop 3 did not abolish β-arrestin 1-dependent internalization but a receptor lacking these basic residues and the carboxy-terminus showed no β-arrestin 1-dependent internalization. Our results suggest that basic residues at the amino-terminal end of intracellular loop 3 or the carboxy-terminal tail are required for β-arrestin dependent internalization.
authors.affiliation: Medical Research Council Research Unit for Receptor Biology, Institute of Infectious Disease and Molecular Medicine and Division of Medical Biochemistry, Faculty of Health Sciences, University of Cape Town, Observatory, 7925 Cape Town, South Africa; School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Medical School, 7 York Road, Parktown 2193, Johannesburg, South Africa.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Madziva
authors.affiliation: Medical Research Council Research Unit for Receptor Biology, Institute of Infectious Disease and Molecular Medicine and Division of Medical Biochemistry, Faculty of Health Sciences, University of Cape Town, Observatory, 7925 Cape Town, South Africa.
authors.forename: Nonhlanhla N
authors.initials: NN
authors.lastname: Mkhize
authors.affiliation: Medical Research Council Research Unit for Receptor Biology, Institute of Infectious Disease and Molecular Medicine and Division of Medical Biochemistry, Faculty of Health Sciences, University of Cape Town, Observatory, 7925 Cape Town, South Africa; School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Medical School, 7 York Road, Parktown 2193, Johannesburg, South Africa.
authors.forename: Colleen A
authors.initials: CA
authors.lastname: Flanagan
authors.affiliation: Medical Research Council Research Unit for Receptor Biology, Institute of Infectious Disease and Molecular Medicine and Division of Medical Biochemistry, Faculty of Health Sciences, University of Cape Town, Observatory, 7925 Cape Town, South Africa. Electronic address: arieh.katz@uct.ac.za.
authors.forename: Arieh A
authors.initials: AA
authors.lastname: Katz
mesh_terms: D000818:Animals; D019390:Arrestins / Q000378:metabolism*; D019556:COS Cells; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D011966:Receptors, LHRH / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D007295:Inositol Phosphates; D011966:Receptors, LHRH; D000071557:beta-Arrestins
keywords: ERK; G protein-coupled receptor kinase; GnRH receptor; Internalization; β-Arrestin