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Amino Acids 855 to 876 of the Rodent Metabotropic Glutamate Receptor, mGluR5, C Terminal Domain Are Responsible for Its Inner Nuclear Membrane Localization
Date of Award
Doctor of Philosophy (PhD)
ABSTRACT OF THE DISSERTATION
Traditionally G-protein coupled receptors (GPCR) are thought to be located on
the cell surface and to transmit extracellular signals into the cytoplasm. A growing
number of GPCRs, however, have been localized to several subcellular compartments
including the inner nuclear membrane (INM). One such receptor is the metabotropic
glutamate receptor 5 (mGluR5) which is not only expressed on the plasma membrane
(PM) but is also expressed on the INM mediating Ca2+ changes in the nucleoplasm by
coupling with Gq/11. In the present study, we identified a region in the proximal part of
the mGluR5 C terminus (amino acids 855-876) which is required for INM localization of
the receptor. Specifically, replacement of intracellular C terminus of another PM GPCR,
GABAB2, with the mGluR5 C terminus led to the nuclear membrane (NM) localization of
the chimeric receptor. Further, immunocytochemistry, fractionation and Ca2+ imaging
techniques revealed that mGluR5 amino acids 855-876 are required for INM localization.
Although these amino acids contain a small basic amino acid stretch akin to bona fide
nuclear localization sequences, their mutation did not prevent INM localization. These
data suggest that mGluR5 either uses a non-canonical mechanism to localize to the INM
and/or that it diffuses there and is subsequently anchored via other interactions. A
retention model is supported by immunoprecipitation and chromatin immunoprecipitation
experiments showing that mGluR5 interacts with nuclear resident biomolecules like
Lamin B1 and chromatin. Taken together, this study defines a region in mGluR5 C
terminus required for its INM localization and suggests that nuclear retention is an
important mechanism in this localization process.
Chair and Committee
Karen L O'Malley
Thomas J Baranski, Narasimhan Gautam, Robert W Gereau, Phyllis I Hanson, Didier Hodzic
Sergin, Ismail, "Amino Acids 855 to 876 of the Rodent Metabotropic Glutamate Receptor, mGluR5, C Terminal Domain Are Responsible for Its Inner Nuclear Membrane Localization" (2012). Arts & Sciences Electronic Theses and Dissertations. 94.