The Formate-Nitrite Transporter (FNT) Family belongs to the Major Intrinsic Protein (MIP) Superfamily. FNT family members have been sequenced from Gram-negative and Gram-positive bacteria, archaea, yeast, plants and lower eukaryotes. The prokaryotic proteins of the FNT family probably function in the transport of the structurally related compounds, formate and nitrite.