The α-Subunit of the Colonic H+,K+-ATPase Assembles with β1-Na+,K+-ATPase in Kidney and Distal Colon

Conversion of the Low Affinity Ouabain-binding Site of Non-gastric H,K-ATPase into a High Affinity Binding Site by Substitution of Only Five Amino Acids

“…No specific ␤-subunit for the non-gastric H,K-ATPase has been found. Most studies support the idea that the ␤ 1 -subunit of Na,KATPase fulfills this function (7)(8)(9)(10).…”

Phosphorylation of S955 at the Protein Kinase A Consensus Promotes Maturation of the α Subunit of the Colonic H+,K+-ATPase

“…The gastric H ϩ ,K ϩ -ATPase (HK␣ 1 ) assembles with a unique ␤ subunit in the kidney and the stomach (␤ G ) (8), whereas ␣ 1 -Na ϩ ,K ϩ -ATPase (NK␣ 1 ) assembles specifically with ␤ 1 -Na ϩ ,K ϩ -ATPase (NK␤ 1 ) (9). HK␣ 2 , in contrast, does not assemble with a unique ␤ subunit but rather assembles with NK␤ 1 in the renal medulla, the distal colon (10,11), and Sf9 cells (12). In addition to these differences, members of the X ϩ ,K ϩ -ATPase family of transporters exhibit different pharmacologic inhibitor profiles.…”

The non-gastric H,K-ATPase as a tool to study the ouabain-binding site in Na,K-ATPase

“…The phylogenic distance between the catalytic subunits of Na,K-ATPase, gastric H,K-ATPase and nongastric H,K-ATPase is about similar. There are three genes that code for β-subunits of Na,K-ATPase (β [1][2][3] ) and one for the β-subunit of gastric H,K-ATPase (β HK ). The nongastric H,K-ATPase has no own β-subunit but most likely uses the β 1 -subunit of Na,K-ATPase [2][3][4].…”

“…There are three genes that code for β-subunits of Na,K-ATPase (β [1][2][3] ) and one for the β-subunit of gastric H,K-ATPase (β HK ). The nongastric H,K-ATPase has no own β-subunit but most likely uses the β 1 -subunit of Na,K-ATPase [2][3][4]. Both Na,KATPase (α 1 ) and the gastric H,K-ATPase work optimally with their own subunits (β 1 and β HK , respectively), but still show some activity with each other's β-subunit [5].…”