The extracellular domain of the sodium pump beta isoforms determines complex stability with alpha 1.
Both subunits of the Na,K-ATPase are encoded by several genes giving rise to at least six isozymes. To examine whether beta isoforms assemble with alpha 1 in a selective manner, we have overexpressed wild-type and chimeric beta subunits in L929 cells and examined assembly as a function of resistance towards detergent-mediated dissociation. In the presence of digitonin all beta chimeras coimmunoprecipitate the endogenous alpha 1 subunit. Only beta proteins with the ectodomain of beta 1 coimmunoprecipitate alpha 1 in the presence of Triton X-100. All beta chimeras stimulate Na,K-ATPase activity in L929 cells. These data indicate that the beta subunit ectodomains mediate interactions with alpha 1 and influence the stability of this complex.
Pontiggia
L
L
Swiss Federal Institute of Technology, ETH Center, Zurich, Switzerland.
Gloor
S M
SM
D000818:Animals; D002460:Cell Line; D004072:Digitonin / Q000737:chemistry; D005110:Extracellular Space; D007527:Isoenzymes / Q000737:chemistry*; D046911:Macromolecular Substances; D051379:Mice; D011993:Recombinant Fusion Proteins; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry*; D013329:Structure-Activity Relationship; D014162:Transfection
D007527:Isoenzymes; D046911:Macromolecular Substances; D011993:Recombinant Fusion Proteins; D000254:Sodium-Potassium-Exchanging ATPase; D004072:Digitonin