Immunoblot analysis of ALAS-E transfected into QT6 fibroblasts. Extracts of wild type ALAS-E and V¹⁹⁰ mutant ALAS-E expressed in QT6 were analyzed. Lane 1 represents nontransfected QT6 cells. Two major bands were seen in the mitochondrial fraction of cells transfected with wild type ALAS2 cDNA (lane 2). The larger band (64 kD) corresponds to the human ALAS-E precursor and the smaller band (58 kD) corresponds to the mature ALAS-E. In the V¹⁹⁰ mutant fraction (lane 3), two bands are detected whose sizes are estimated to be 59.5 and 59 kD.