The α(2A)-adrenergic receptor (α(2A)AR) is polarized to the basolateral membrane of Madin-Darby canine kidney cells via direct targeting. Examination of mutant α(2A)AR reveals that direct delivery is independent of NH2- terminal glycosylation, COOH-terminal acylation, or protein sequences within the large third cytoplasmic loop or COOH-terminal tail. Combined mutation of these structural features also does not perturb α(2A)AR delivery, suggesting that a three-dimensional structure imparted by non-contiguous endofacial sequences does not confer α(2A)AR targeting and that motifs in or near the bilayer must be involved in targeting of the α(2A)AR. Mutation of a conserved Asp residue in transmembrane two that alters receptor-G-protein interactions also does not impair α(2A)AR targeting. Finally, modification of sequences in transmembrane seven that resemble tyrosine-containing endocytosis motifs utilized for targeting by some proteins does not perturb α(2A)AR sorting. Interestingly, deletion of the large third cytoplasmic loop of the α(2A)AR decreases receptor half-life on the basolateral surface from approximately 11 to 4.5 h without altering the ability of the α(2A)AR to couple to G-proteins. These data suggest that although targeting of the α(2A)AR likely involves bilayer sequences, the third cytoplasmic loop may contain structural features that promote stabilization of the α(2A)AR on the basolateral surface of Madin-Darby canine kidney cells.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of Biological Chemistry|
|State||Published - 1994|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology