FGSC #521

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Reporting Genes: am

Species: crassa

Allele: 32213

Alternate Strain Number: 32213-2B-2A

Mutagen: UV

Depositor: RWB

Linkage Group: VR

Mating Type: A

Species Number: 10

Genetic Background: M

Opposite Mating Type: 1184

Deposit Sheet ↗

Genes

Locus	Cultural Requirements	Link Group	Type
am	VR. Right of ure-2 (2%) and sp (4 to 8%). Left of gul-1(<<1%) and ace-5(<1%) (122, 570, 579, 998). (R.W. Barratt, (cited in reference 1036) Structural gene for nicotinamide adenine dinucleotide phosphate (NADP)-glutamate dehydrogenase (336) (see Fig. 19), for which a complete 452-residue amino acid sequence has been obtained (465). Requires a source of alpha-amino nitrogen for growth, alanine being a good supplement (e.g., reference 997). Readily scorable at 25 C; leaky at 34°C (42). Leaky growth and adaptation on minimal medium are prevented by 0.02 M glycine (782, 783) or by en(am)-1, en(am)-2, or nit-2, q.v. The ammutants show abnormal regulation of reduced nicotinamide adenine dinucleotide (NADH)-glutamate dehydrogenase and are synergistic with nit-2 in this effect (226). Some am alleles (e.g., RU1) suppress the pyrimidine requirement caused by pyr-3 (CPS- ACT+) mutations (1137). Used for the first demonstration of complementation between alleles in vivo (344) (simultaneous with independent demonstration with ad-4). In vitro complementation (342). Used for studies of complementation mechanism (199, 200, 1120). Used for fine-structure mapping (337, 338). Control of intralocus recombination by rec-3(996-998). Used to study colinearity of the gene and gene product, internal suppressors (105, 340, 465), and the action of supersuppressors (954, 955). The functional defects in several mutant enzymes with single amino acid replacements have been defined: am1 mutant enzymes fail to bind NADPH (1120); am2, am3, am19, am130, and am131 enzymes are stabilized in the inactive conformational form (30, 200, 336, 556, 1044), and all are complementable by am1; am14 is osmotically reparable and is thought to have unstable quaternary structure (340). Used in a study showing glutamine to have a role as corepressor of uricase synthesis (1118). Used to study nitrogen assimilation and metabolism (503) and nitrogen metabolite repression (186, 291). Efficient procedure for selecting new am mutants (551). Spectrum of ultraviolet irradiation (UV)- and nitrous acid-induced mutants (554). Allele am17 has a chain-terminating codon of either the amber or ochre type at residue 313 of glutamate dehydrogenase, based on amino acid replacements in revertants and by ssu-1 (956). Allele 6 is a frameshift mutation with an insertion in the Ser5 codon (985). Allele 126 is highly unstable (553). Allele 132 is a deletion (1162). The am+ gene has been cloned in Escherichia coli(J.R.S. Fincham, personal communication) and transformed back into Neurospora (J.A. Kinsey, personal communication).	VR	B