The present invention relates to a newly identified human aminopeptidase. The invention also relates to polynucleotides encoding the aminopeptidase. The invention further relates to methods using the aminopeptidase polypeptides and polynucleotides as a target for diagnosis and treatment in aminopeptidase-related disorders. The invention further relates to drug-screening methods using the aminopeptidase polypeptides and polynucleotides to identify agonists and antagonists for diagnosis and treatment. The invention further encompasses agonists and antagonists based on the aminopeptidase polypeptides and polynucleotides. The invention further relates to procedures for producing the aminopeptidase polypeptides and polynucleotides.