Abstract
OPINION article Front. Physiol., 10 October 2013Sec. Membrane Physiology and Membrane Biophysics https://doi.org/10.3389/fphys.2013.00291
Highlights
A metabolon has been defined as a “temporary, structural-functional, supramolecular complex of sequential metabolic enzymes and cellular structural elements, in which metabolites are passed from one active site to another without complete equilibration with the bulk cellular fluids” (Srere, 1985, 1987)
First evidence that the non-catalytic interaction between monocarboxylate transporters (MCTs) and CAII depends on a direct interaction between the two proteins was shown by injection of CAII that was bound to an antibody prior to the injection
From this it was concluded that the interaction between MCT2 and CAIV may not depend on a direct binding between MCT2 and CAIV, as suggested for MCT1/4 and CAII, but may be mediated by binding of CAIV to embigin, which could act as a mediator for CAIV-induced transport enhancement of MCT2 (Klier et al, 2011)
Summary
A metabolon has been defined as a “temporary, structural-functional, supramolecular complex of sequential metabolic enzymes and cellular structural elements, in which metabolites are passed from one active site to another without complete equilibration with the bulk cellular fluids” (Srere, 1985, 1987) This substrate channeling should decrease transit time of intermediates, prevent loss of intermediates by diffusion, protect labile intermediates from solvent, and prevent entrance of intermediates into competing metabolic pathways (Miles et al, 1999). Exchanger NHE1, the Na+/HCO−3 cotransporter NBCe1, and various monocarboxylate transporters (MCTs) have been demonstrated to physically and/or functionally interact with isoforms of carbonic anhydrase (CA) to form a “transport metabolon.” This functional interaction includes an increase in transport activity, and may enhance both the rate and the capacity of ion/metabolite transport in tissues where these membrane transporters and enzymes are co-localized. Physical and functional interaction with extracellular CAIV could be demonstrated for the Na+/HCO−3 cotransporter NBCe1 (Alvarez et al, 2003): Transport activity of NBCe1 was determined by fluorometric pH www.frontiersin.org
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