Interaction with 14‐3‐3 proteins promotes functional expression of the potassium channels TASK‐1 and TASK‐3

Abstract

The two-pore-domain potassium channels TASK-1, TASK-3 and TASK-5 possess a conserved C-terminal motif of five amino acids. Truncation of the C-terminus of TASK-1 strongly reduced the currents measured after heterologous expression in Xenopus oocytes or HEK293 cells and decreased surface membrane expression of GFP-tagged channel proteins. Two-hybrid analysis showed that the C-terminal domain of TASK-1, TASK-3 and TASK-5, but not TASK-4, interacts with isoforms of the adapter protein 14-3-3. A pentapeptide motif at the extreme C-terminus of TASK-1, RRx(S/T)x, was found to be sufficient for weak but significant interaction with 14-3-3, whereas the last 40 amino acids of TASK-1 were required for strong binding. Deletion of a single amino acid at the C-terminal end of TASK-1 or TASK-3 abolished binding of 14-3-3 and strongly reduced the macroscopic currents observed in Xenopus oocytes. TASK-1 mutants that failed to interact with 14-3-3 isoforms (V411*, S410A, S410D) also produced only very weak macroscopic currents. In contrast, the mutant TASK-1 S409A, which interacts with 14-3-3-like wild-type channels, displayed normal macroscopic currents. Co-injection of 14-3-3z cRNA increased TASK-1 current in Xenopus oocytes by about 70 %. After co-transfection in HEK293 cells, TASK-1 and 14-3-3z (but not TASK-1DC5 and 14-3-3z) could be co-immunoprecipitated. Furthermore, TASK-1 and 14-3-3 could be coimmunoprecipitated in synaptic membrane extracts and postsynaptic density membranes. Our findings suggest that interaction of 14-3-3 with TASK-1 or TASK-3 may promote the trafficking of the channels to the surface membrane.

Protein Kinase A Phosphorylation of Human Phosphodiesterase 3B Promotes 14-3-3 Protein Binding and Inhibits Phosphatase-catalyzed Inactivation

“…Ser-73 was within a predicted PKA consensus sequence in the 90-amino acid fragment used in the yeast two-hybrid analyses. Ser-296 was within a PKA consensus sequence that allowed 14-3-3 proteins to traffic the two-pore domain potassium channel protein TASK-1 (32). Another potential PKA site identified in silico, Ser-13, was not studied.…”

Adenomatous polyposis coli plays a key role, in vivo, in coordinating assembly of the neuronal nicotinic postsynaptic complex

“…14-3-3 isoforms (sigma and zeta) bind to APC (Jin et al, 2004;Meek et al, 2004). 14-3-3 is present in postsynaptic densities isolated from rat brain (Martin et al, 1994;Couve et al, 2001;Rajan et al, 2002). Interaction with 14-3-3 promotes the surface expression of selected neurotransmitter receptors and ion channels (Jeanclos et al, 2001;Rajan et al, 2002;Exley et al, 2006).…”

“…14-3-3 is present in postsynaptic densities isolated from rat brain (Martin et al, 1994;Couve et al, 2001;Rajan et al, 2002). Interaction with 14-3-3 promotes the surface expression of selected neurotransmitter receptors and ion channels (Jeanclos et al, 2001;Rajan et al, 2002;Exley et al, 2006). In particular, 14-3-3 binds directly to another neuronal nAChR subunit, the long cytoplasmic loop of α4, a major subtype in the CNS, and this interaction increases surface expression of α4*nAChRs in heterologous cell expression studies (Jeanclos et al, 2001;Exley et al, 2006).…”

Intracellular Trafficking of KA2 Kainate Receptors Mediated by Interactions with Coatomer Protein Complex I (COPI) and 14-3-3 Chaperone Systems

“…In KCNK3 and Kir6.2 channels, COPImediated ER retention was opposed by 14-3-3 proteins, a family of soluble proteins with diverse cellular functions (11,12). 14-3-3 proteins also promoted plasma membrane expression of other integral proteins such as nicotinic acetylcholine receptors (14) and TASK-1 and TASK-3 potassium channels (15).…”