Primary Information
BoMiProt ID	Bomi44
Protein Name	Sodium/potassium-transporting ATPase subunit beta-3
Organism	Bos taurus
Uniprot ID	Q3T0C6
Milk Fraction	MFGM
Ref Sequence ID	NP_001030470.1
Aminoacid Length	279
Molecular Weight	31521
FASTA Sequence	Download
Gene Name	ATP1B3
Gene ID	532844
Protein Existence Status	Reviewed: Experimental evidence at transcript level
Secondary Information
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) N-glycosylation, O-glycosylation, Phosphorylation
Predicted Disorder Regions	NA
DisProt Annotation
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
Linking IDs
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.