Muscle fructose-1,6-bisphosphatase (FBP2), a regulatory enzyme of glyconeogenesis, binds to mitochondria where it interacts with proteins involved in regulation of energy homeostasis. Here, we show that the quaternary structure of FBP2 plays a crucial role in this interaction, and that the AMP-driven transition of the FBP2 subunit arrangement from active to inactive precludes its association with the mitochondria. Moreover, we demonstrate that truncation of the evolutionarily conserved N-terminal residues of FBP2 results in a loss of its mitochondria-protective functions. This strengthens the recently raised hypothesis that FBP2 evolved as a regulator not only for glycogen storage but also for mitochondrial function in contracting muscle.
Keywords: AMP; Fructose-1,6-bisphosphatase; Mitochondria; Quaternary structure.
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