Abstract
A highly conserved sequence motif (4 tyrosines and 1 proline: YYPYY) of the Na+-K+-adenosinetriphosphatase (ATPase) β1-subunit ectodomain has been mutagenized to study its possible role in α/β-assembly and sodium pump function. Single as well as double tyrosine mutants (tyrosine to phenylalanine: Y to F) of Xenopus laevis β1-subunits are able to associate with α1-subunits and form functional Na-K pumps at the plasma membrane that are indistinguishable from wild-type α1,β1-Na-K pumps (as assessed by measurements of ouabain binding, 86Rb flux, Na-K pump current, and activation by external potassium). In contrast, a single proline mutation (proline to glycine: P244G) reduced by >90% the proper assembly and function of Na+-K+-ATPase, despite a normal rate of synthesis and core glycosylation. Our data indicate that proline-244 plays a critical role in the proper folding of the β-subunit and its ability to associate efficiently with the α1-subunit in the endoplasmic reticulum.
Original language | English (US) |
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Pages (from-to) | C1169-C1174 |
Journal | American Journal of Physiology - Cell Physiology |
Volume | 265 |
Issue number | 4 34-4 |
State | Published - 1993 |
Externally published | Yes |
Keywords
- Xenopus laevis
- functional expression
- oocyte
- potassium activation
- sodium pump
- sodium-potassium-adenosinetriphosphatase
- α-subunit
ASJC Scopus subject areas
- Physiology
- Cell Biology