Expression and purification of the FXYD family proteins PLM, CHIF, and Mat8. (A) Amino acid sequences of PLM, CHIF and Mat8. The FXYD homology domain (FH) encompasses the FXYD consensus sequence (in bold), and the transmembrane domain (TM). (B) Protein fractions at different stages of the purification protocol were analyzed on Coomassie stained 16% SDS-PAGE. Lane 1: Entire cell before IPTG induction. Lane 2: Entire cell after IPTG induction with the fusion protein band at 21 kDa. Lane 3: Isolated inclusion bodies enriched in fusion protein. Lane 4: Fusion protein isolated by Ni affinity chromatography. Lane 5: His9-TrpΔLE fusion partner and PLM resulting from CNBr cleavage of the fusion protein. Lane 6: Purified PLM. Lane 7: Purified CHIF. Lane 8: Purified Mat8. (C) MALDI-TOF mass spectra of purified PLM (8379 Da), CHIF (7086 Da), and Mat8 (7112 Da).