STRUCTURE–FUNCTION RELATIONSHIPS OF NA+/K+-PUMPS EXPRESSED INXENOPUSOOCYTES

✍ Scribed by WOLFGANG SCHWARZ; LARISA A. VASILETS

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 520 KB
• Volume: 20
• Category: Article
• ISSN: 1065-6995
• DOI: 10.1006/cbir.1996.0010

✦ Synopsis

During the last years we have examined structure-function relationships in the Na + /K + -ATPase with respect to interactions of the external cations with the pump molecule. We have analysed in voltage-clamp experiments the influence of extracellular Na + and K + on the current generated by Na + /K + -pumps expressed in Xenopus oocytes. Our results demonstrated that external Na + and K + have to pass an access channel in the electrical field of the membrane to reach their binding sites. This external access, therefore, is voltage-dependent and is affected by lysine residues within the cytoplasmic N-terminus, by glutamic acid residues in intramembraneous domains, the ouabain sensitivity and phosphorylation by protein kinases.