Nitrogen Fixation 1 Homolog (NFS1)

NFS1 uses alternate in-frame translation initiation sites to generate mitochondrial forms and cytoplasmic/nuclear forms. Selection of the alternative initiation sites is determined by the cytosolic pH. The encoded protein belongs to the class-V family of pyridoxal phosphate-dependent aminotransferases.

In human cells, different forms of NIFS that localize either to mitochondria or to the cytosol and nucleus are synthesized from a single transcript through initiation at alternative in-frame AUGs, and initiation site selection varies according to the pH of the medium or cytosol. Thus, this form of translational regulation permits rapid redistribution of NIFS proteins into different compartments of the cell in response to changes in metabolic status.