title: Gene dosage effects in polyploid strains of Saccharomyces cerevisiae containing gua-1 wild-type and mutant alleles.
abstract: Triploid and tetraploid Saccharomyces strains containing different combinations of a gua-1 mutant allele and the corresponding wild type were prepared. The cultivation of the different strains in media upon which the mutant fails to grow leads to a pronounced growth rate response to the dosage of the wild-type allele. Proportionality between the specific activity of the guanosine 5'-monophosphate synthetase and the wild-type dosage was reavealed. Inosine 5'-monophosphate dehydrogenase, the precursor enzyme in the pathway, is derepressed in a sigmoid manner when the wild-type dosage is reduced, whereas the activity of cytosine deaminase, investigated as a reference enzyme, is less affected.
mesh_terms: D000483:Alleles; D002474:Cell-Free System; D003564:Cytidine Deaminase / Q000378:metabolism; D006147:Guanine / Q000378:metabolism*; D006150:Guanine Nucleotides; D007168:IMP Dehydrogenase / Q000378:metabolism; D008025:Ligases / Q000378:metabolism; D009154:Mutation; D011123:Polyploidy; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*
chemical_list: D006150:Guanine Nucleotides; D006147:Guanine; D007168:IMP Dehydrogenase; D003564:Cytidine Deaminase; D008025:Ligases