CD 63 interacts with the carboxy terminus of the colonic H - K - ATPase to increase plasma membrane localization and 86 Rb uptake

Codina, Juan, Jian Li, and Thomas D. DuBose, Jr. CD63 interacts with the carboxy terminus of the colonic H -K -ATPase to increase plasma membrane localization and Rb uptake. Am J Physiol Cell Physiol 288: C1279–C1286, 2005. First published January 12, 2005; doi:10.1152/ajpcell.00463.2004.—The carboxy terminus (CT) of the colonic H -K -ATPase is required for stable assembly with the -subunit, translocation to the plasma membrane, and efficient function of the transporter. To identify protein-protein interactions involved in the localization and function of HK 2, we selected 84 amino acids in the CT of the -subunit of mouse colonic H -K ATPase (CT-HK 2) as the bait in a yeast two-hybrid screen of a mouse kidney cDNA library. The longest identified clone was CD63. To characterize the interaction of CT-HK 2 with CD63, recombinant CT-HK 2 and CD63 were synthesized in vitro and incubated, and complexes were immunoprecipitated. CT-HK 2 protein (but not CTHK 1) coprecipitated with CD63, confirming stable assembly of HK 2 with CD63. In HEK-293 transfected with HK 2 plus 1-Na K -ATPase, suppression of CD63 by RNA interference increased cell surface expression of HK 2/NK 1 and Rb uptake. These studies demonstrate that CD63 participates in the regulation of the abundance of the HK 2-NK 1 complex in the cell membrane.