Catalyzes the NAD-dependent oxidation of 2-aminomuconic semialdehyde of the kynurenine metabolic pathway in L-tryptophan degradation. 2-aminomuconate 6-semialdehyde + H2O + NAD(+) = (2Z,4E)-2-aminomuconate + 2 H(+) + NADH Amino-acid degradation; L-kynurenine degradation. Highly expressed in adult kidney and liver. Detected at lower levels in fetal liver and kidney. Lacks enzymatic activity. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. Belongs to the aldehyde dehydrogenase family. Originally described as a retinal dehydrogenase based on its ability to preferentially oxidize 9-cis-retinal (PubMed:11007799). It has been reassigned to a 2-aminomuconic semialdehyde dehydrogenase (PubMed:29703752). Wrong choice of CDS.