Investigation of two yeast genes encoding putative isoenzymes of phosphoglycerate mutase.
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GPM1 is the only functional phosphoglycerate mutase in yeast; GPM2 and GPM3 were detected as homologous sequences during genome sequencing.
"Our previous data indicated that GPM1 encodes the only functional phosphoglycerate mutase in yeast. However, in the course of the yeast genome sequencing project, two homologous sequences, designated GPM2 and GPM3, were detected."
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The catalytic residues of the mutase active site are conserved in GPM3.
"Key residues in the deduced amino acid sequence, shown to be involved in catalysis for Gpm1 (i.e. His8, Arg59, His181) are conserved in both enzymes."
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Forced high-level expression of GPM3 partially complemented gpm1 defects but did not restore any detectable enzymatic activity.
"Higher level expression under the control of the yeast PFK2 promoter partially complemented the gpm1 defects, without restoring detectable enzymatic activity."
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Deletion of GPM2 and/or GPM3 produced no growth lesions and no change in key metabolite levels; both are probable non-functional homologs arising by duplication.
"deletion of either GPM2 or GPM3, or the two deletions in concert, did not produce any obvious lesions for growth on a variety of different carbon sources, nor did they change the levels of key intermediary metabolites."