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This Article Full Text Full Text (PDF) All Versions of this Article: 74/5/788    most recent biolreprod.105.048157v2 biolreprod.105.048157v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Navratil, A. M. Articles by Clay, C. M. Search for Related Content PubMed PubMed Citation Articles by Navratil, A. M. Articles by Clay, C. M. Agricola Articles by Navratil, A. M. Articles by Clay, C. M.

Differential Impact of Intracellular Carboxyl Terminal Domains on Lipid Raft Localization of the Murine Gonadotropin-Releasing Hormone Receptor

Department of Biomedical Sciences,² Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, Colorado 80523 Department of Endocrinology,³ Utrecht University, 3584 Utrecht, The Netherlands

ABSTRACT

The mammalian type I GNRH receptor (GNRHR) is unique among G protein-coupled receptors (GPCRs) because of the absence of an intracellular C-terminus. Previously, we have found that the murine GNRHR is constitutively localized to low-density membrane microdomains termed lipid rafts. As such, association of the GNRHR with lipid rafts may reflect both a loss (C-terminus) and a gain (raft association address) of structural characteristics. To address this, we fused either the full-length C-terminus from the nonraft-associated LH receptor (LHCGR; GNRHR-LF) or a truncated (t631) LHCGR C-terminus to the GNRHR. These chimeric receptors are trafficked to the plasma membrane, bind ligand, and display increased agonist-induced receptor internalization, but they do not partition into lipid rafts. Thus, a heterologous C-terminus from a nonraft-associated GPCR redirects localization of the GNRHR to nonraft domains. In contrast to the murine GNRHR, the catfish GNRHR (cfGNRHR) possesses an intracellular C-terminus. We found that the cfGNRHR was localized to lipid rafts and that the cfGNRHR C-terminus did not alter raft localization of the mammalian receptor. Consistent with placement in different lipid microenvironments within the plasma membrane, fluorescence recovery after photobleaching revealed different lateral diffusion phenotypes of the raft-associated GNRHR and cfGNRHR versus the nonraft-associated GNRHR-LF fusion protein. We conclude that whereas an intracellular C-terminus is capable of redirecting the GNRHR to nonraft compartments, this is not a generalized feature of GPCR C-terminal tails. Thus, constitutive raft localization of the GNRHR is not simply a result of the loss of an intracellular C-terminus.

gonadotropin-releasing hormone receptor, mechanisms of hormone action, pituitary

¹ Correspondence: Colin M. Clay, Department of Biomedical Sciences-ARBL, 1683 Campus Delivery, Fort Collins, CO 80523. FAX: 970 491 3557; colin.clay{at}colostate.edu