|Protein Name||Sodium/potassium-transporting ATPase subunit beta-3|
|Ref Sequence ID||NP_001030470.1|
|Protein Existence Status||Reviewed: Experimental evidence at transcript level|
|Presence in other biological fluids/tissue/cells||highly expressed in kidneys; brain; sperm cells express a unique Na,K-ATPase isoform|
|Protein Function||αsubunit is responsible for the catalytic activity of the Na,K-ATPase while the ß subunit is important in the maturation and transport of the enzyme to the plasma membrane; maintains the gradient of sodium and potassium across plasma membrane; main kidney functions are to filter the blood of waste products to reabsorb glucose and amino acids, to regulate electrolytes and to maintain pH; in sperm cells - regulation of ions and membrane potential is crucial for motility and the acrosome reaction and is essential for male fertility; in brain- required to fire action potential|
|Biochemical Properties||beta subunit has three conserved disulfide bonds in the extracellular domain, which are important for forming a stable pump; Na,K-ATPase exists as a heterodimer consisting of a large catalytic α subunit and a smaller glycoslated ß subunit; α subunit possesses eight transmembrane domains and the ß subunit only one; Ouabain binds at the permeation pathway of the Na /K ATPase|
|Significance in milk||nutrient transport systems for milk precursors and constituents|
|PTMs||ß domain has domain has three, eight, and two glycosylation sites in beta1, 2, and 3, respectively|
| Site(s) of PTM(s) |
|Predicted Disorder Regions||NA|
|TM Helix Prediction||1TMH; (38-60)|
|Significance of PTMs||Removal of the glycosylations causes retention in the endoplasmatic reticulumof beta2, but not of beta1 or 3, suggesting that the glycosylations play individual roles in the different isoforms|
|Bibliography||1. Jimenez, T., McDermott, J. P., Sánchez, G., & Blanco, G. (2011). Na, K-ATPase α4 isoform is essential for sperm fertility. Proceedings of the National Academy of Sciences of the United States of America, 108(2), 644–649. https://doi.org/10.1073/pnas.1016902108. |
2. Tokhtaeva, E., Clifford, R. J., Kaplan, J. H., Sachs, G., & Vagin, O. (2012). Subunit isoform selectivity in assembly of Na,K-ATPase α-β heterodimers. The Journal of Biological Chemistry, 287(31), 26115–26125. https://doi.org/10.1074/jbc.M112.370734.
3. Noguchi, S., Mutoh, Y., & Kawamura, M. (1994). The functional roles of disulfide bonds in the beta-subunit of (Na,K)ATPase as studied by site-directed mutagenesis. FEBS Letters, 341(2–3), 233–238. https://doi.org/10.1016/0014-5793(94)80463-x.
4. El Mernissi, G., & Doucet, A. (1984). Quantitation of [3H]ouabain binding and turnover of Na-K-ATPase along the rabbit nephron. American Journal of Physiology-Renal Physiology, 247(1), F158–F167. https://doi.org/10.1152/ajprenal.1984.247.1.F158.
5. Sandtner, W., Egwolf, B., Khalili-Araghi, F., Sánchez-Rodríguez, J. E., Roux, B., Bezanilla, F., & Holmgren, M. (2011). Ouabain binding site in a functioning Na+/K+ ATPase. The Journal of Biological Chemistry, 286(44), 38177–38183. https://doi.org/10.1074/jbc.M111.267682.
6. Price, E. M., & Lingrel, J. B. (1988). Structure-function relationships in the Na,K-ATPase alpha subunit: site-directed mutagenesis of glutamine-111 to arginine and asparagine-122 to aspartic acid generates a ouabain-resistant enzyme. Biochemistry, 27(22), 8400–8408. https://doi.org/10.1021/bi00422a016.