RT Journal Article
SR Electronic
T1 The Dopamine D3 Receptor Interacts with Itself and the Truncated D3 Splice Variant D3nf: D3-D3nf Interaction Causes Mislocalization of D3 Receptors
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 677
OP 683
DO 10.1124/mol.58.4.677
VO 58
IS 4
A1 Kelly D. Karpa
A1 Ridwan Lin
A1 Nadine Kabbani
A1 Robert Levenson
YR 2000
UL http://molpharm.aspetjournals.org/content/58/4/677.abstract
AB We have generated a stable cell line expressing FLAG epitope-tagged D3 dopamine receptors and used this cell line to study D3 receptor-protein interactions. To analyze protein interactions, we separately introduced into the stable cell line either D3 receptors carrying an hemagglutinin (HA) epitope tag, or an HA-tagged version of the D3 receptor splice variant D3nf. A combination of confocal laser microscopy and coimmunoprecipitation was used to assay the formation and expression pattern of D3-D3 homodimers or D3-D3nf heterodimers. When coexpressed in HEK 293 cells, FLAG- and HA-tagged D3 receptors exhibited a similar plasma membrane distribution. Using an HA epitope tag-specific antibody, we coimmunoprecipitated HA- and FLAG-tagged D3 receptors, suggesting that D3 receptors are capable of forming homodimers. Epitope-tagged D3nf polypeptides exhibited a markedly different cellular distribution than D3 receptors. When expressed in HEK 293 cells, either alone or in combination with FLAG-tagged D3 receptors, D3nf exhibited a punctate perinuclear distribution. When D3nf was introduced into the stable D3-expressing cell line, D3 receptors were no longer visualized at the plasma membrane. Instead, D3 and D3nf showed a similar, predominantly cytosolic, localization. Using the HA-specific antibody, we were able to coimmunoprecipitate D3 and D3nf polypeptides from transfected cells. These data suggest the existence of physical interaction between D3 and D3nf. This interaction appears to result in the mislocalization of D3 receptors from the plasma membrane to an intracellular compartment, a finding that could be of significance in the etiology of schizophrenia.