Carbonic anhydrases enhance activity of endogenous Na-H exchangers and not the electrogenic Na/HCO₃ cotransporter NBCe1-A, expressed in Xenopus oocytes.

ABSTRACT:

Key points

According to the HCO3- metabolon hypothesis, direct association of cytosolic carbonic anhydrases (CAs) with the electrogenic Na/HCO₃ cotransporter NBCe1-A speeds transport by regenerating/consuming HCO3- . The present work addresses published discrepancies as to whether cytosolic CAs stimulate NBCe1-A, heterologously expressed in Xenopus oocytes. We confirm the essential elements of the previous experimental observations, taken as support for the HCO3- metabolon hypothesis. However, using our own experimental protocols or those of others, we find that NBCe1-A function is unaffected by cytosolic CAs. Previous conclusions that cytosolic CAs do stimulate NBCe1-A can be explained by an unanticipated stimulatory effect of the CAs on an endogenous Na-H exchanger. Th

SUBMITTER: Moss FJ 

PROVIDER: S-EPMC7747792 | biostudies-literature | 2020 Dec

REPOSITORIES: biostudies-literature