Co-expression of metabotropic glutamate receptor type 1alpha with homer-1a/Vesl-1S increases the cell surface expression of the receptor.
Homer-1a is a 30 kDa protein that forms part of a family of conserved Homer-related proteins that interact with the C-termini of the metabotropic glutamate receptors mGluR1alpha and mGluR5a. Analysis of HEK-293 cells by PCR showed that they contained mRNA coding for members of the Homer family with the predominant form being Homer-1b, which is consistent with the immunochemical analysis of these cells. Homer-1a could not be detected by immunochemical analysis. To examine the function of Homer-1a, HEK-293 cells were transfected with cDNA encoding mGluR1alpha or Homer-1a or co-transfected with both cDNAs. When cells were co-transfected with the cDNAs for both proteins, immunofluorescent staining and biotinylation of cell surface molecules revealed a significant increase in the amount of receptor present at the cell surface in contrast to cells transfected with mGluR1alpha cDNA alone. This finding was consistent with a concomitant increase in the production of inositol phosphates after treatment of the doubly transfected cells with agonist. Intracellular immunostaining for both proteins revealed that they were co-localized and underwent a redistribution into a large vesicular compartment when they were co-expressed.
Medical Research Council Anatomical Neuropharmacology Unit, Mansfield Road, Oxford OX1 3TH, U.K.
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F
Ciruela
M M
MM
Soloviev
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McIlhinney
D000818:Animals; D000906:Antibodies / Q000276:immunology; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers; D000072233:Homer Scaffolding Proteins; D006801:Humans; D009479:Neuropeptides / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014162:Transfection
D000906:Antibodies; D002352:Carrier Proteins; D017931:DNA Primers; C000606614:HOMER1 protein, human; D000072233:Homer Scaffolding Proteins; D009479:Neuropeptides; D012333:RNA, Messenger; D018094:Receptors, Metabotropic Glutamate