The gene product is a cytosolic enzyme involved in the production of alpha-aminoadipic acid from alpha-aminoadipic semialdehyde. It is postulated that this enzyme plays a role in lysine metabolism. There is currently debate regarding this enzyme's putative requirement of pyrroloquinoline quinine as an essential cofactor. A related pseudogene has been identified on chromosome 2. [provided by RefSeq, Jan 2010]