Characteristic attributes limiting the transport rates in NCX orthologs.

Authors :: Refaeli B
Hiller R
Khananshvili D
Source :: Biochimica et biophysica acta. Biomembranes [Biochim Biophys Acta Biomembr] 2022 Feb 01; Vol. 1864 (1), pp. 183792. Date of Electronic Publication: 2021 Sep 25.
Publication Year :: 2022
Abstract: The Na <superscript>+/</superscript> Ca <superscript>2+</superscript> exchangers (NCXs) modulate the Ca2+ signaling and homeostasis in health and disease. The transport cycle turnover rates (kcat) and the kcat/Km values of eukaryotic NCXs are ~10 <superscript>4</superscript> -times higher than those of prokaryotic NCXs. Three ion-coordinating residues (out of twelve) differ between eukaryotic NCXs and NCX&#95;Mj. The replacement of three ion-coordinating residues in NCX&#95;Mj does not increase kcat, probably due to the structural rigidity of NCX&#95;Mj. Phospholipids and cholesterol increase (up to 10-fold) the transport rates in the cardiac NCX1.1, but not in NCX&#95;Mj. A lipid environment can partially contribute to the huge kinetic variances among NCXs.<br /> (Copyright © 2021. Published by Elsevier B.V.)