FIGURE 5.

Conserved histidine residues are essential for catalytic function of Ole1p. A, comparison of partial sequences of the membrane desaturases from yeast (NP_011460), rat (NP_114029), mouse (NP_033154), and Arabidopsis (AAM63359). Five conserved His residues within Ole1p are indicated in black circles, and two non-conserved His residues are indicated in gray-filled circles; numbers are relative to the Ole1p sequence. B, schematic representation of the plasmid constructs for expression of Ole1p mutant-Myc under the control of the GAL1 promoter. C, growth of yeast Ole1 deletion strain L8-14C lacking or containing either the wild type Ole1 or mutant forms of the gene in which individual His residues were converted to Ala as indicated. Cultures were replica-plated onto media containing unsaturated fatty acids, or media lacking unsaturated fatty acids (UFA), as indicated.