The K+-dependent (NCKX2) and K+-independent (NCX1) Na+/Ca2+ exchangers exhibit distinct sensitivities to extracellular monovalent cations, likely due to differences in their respective binding site domains.
Sensitivities of the reverse-mode Na+/Ca2+ exchange activity measured as the Na+i-dependent Ca2+ uptake to extracellular monovalent cations K+, Li+, and Na+ were compared between the K+ -dependent (NCKX2) and the K+ -independent Na+/Ca2+ exchanger (NCX1) overexpressed in a fibroblast cell. Interestingly, the exchange activity of NCKX2 was not influenced by Li+ while it was increased by K+. On the contrary, the activity of NCX1 was increased by Li+. Thus, the cation sensitivities to K+ and Li+ markedly differed between NCKX2 and NCX1. In addition, Na+ exerted a significantly smaller inhibitory effect on the activity in NCKX2 than in NCX1. The Na+/Ca2+ exchange activities of NCKX2 and NCX1 are considered to be regulated differentially via the respective binding site domains that have distinct sensitivities to the external monovalent cations.
No takes yet. Share an insight, caveat, or question.
Uehara et al. (2004) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: