Involvement of Golgin-160 in cell surface transport of renal ROMK channel: co-expression of Golgin-160 increases ROMK currents.
The weak inward rectifier potassium channel ROMK is important for water and salt reabsorption in the kidney. Here we identified Golgin-160 as a novel interacting partner of the ROMK channel. By using yeast two-hybrid assays and co-immunoprecipitations from transfected cells, we demonstrate that Golgin-160 associates with the ROMK C-terminus. Immunofluorescence microscopy confirmed that both proteins are co-localized in the Golgi region. The interaction was further confirmed by the enhancement of ROMK currents by the co-expressed Golgin-160 in Xenopus oocytes. The increase in ROMK current amplitude was due to an increase in cell surface density of ROMK protein. Golgin-160 also stimulated current amplitudes of the related Kir2.1, and of voltage-gated Kv1.5 and Kv4.3 channels, but not the current amplitude of co-expressed HERG channel. These results demonstrate that the Golgi-associated Golgin-160 recognizes the cytoplasmic C-terminus of ROMK, thereby facilitating the transport of ROMK to the cell surface. However, the stimulatory effect on the activity of more distantly-related potassium channels suggests a more general role of Golgin-160 in the trafficking of plasma membrane proteins.
Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany. Klaus.Steinmeyer@sanofi-aventis.com
Florian
F
Bundis
Ioana
I
Neagoe
Blanche
B
Schwappach
Klaus
K
Steinmeyer
D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D001693:Biological Transport, Active; D019556:COS Cells; D002460:Cell Line; D002522:Chlorocebus aethiops; D005260:Female; D015723:Gene Library; D000077614:Golgi Matrix Proteins; D006801:Humans; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D009865:Oocytes / Q000378:metabolism; D024661:Potassium Channels, Inwardly Rectifying / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014982:Xenopus laevis
D001324:Autoantigens; C108388:GOLGA3 protein, human; D000077614:Golgi Matrix Proteins; C086989:KCNJ1 protein, human; C510692:Kcnj1 protein, rat; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D024661:Potassium Channels, Inwardly Rectifying; D011994:Recombinant Proteins