Nuclear respiratory factor 1, also known as Nrf1, Nrf-1, NRF1 and NRF-1, encodes a protein that homodimerizes and functions as a transcription factor which activates the expression of some key regulating cellular growth and nuclear genes required for respiration, heme biosynthesis, and mitochondrial DNA transcription and replication. The protein has also been associated with the regulation of neurite outgrowth. Alternate , which encode the same protein, have been characterized. Additional variants encoding different protein isoforms have been described but they have not been fully characterized. Confusion has occurred in bibliographic databases due to the shared symbol of NRF1 for this gene and for "nuclear factor (erythroid-derived 2)-like 1" which has an official symbol of NFE2L1.