Generation of a mouse model for arginase II deficiency by targeted disruption of the arginase II gene

Mammals express two isoforms of arginase, designated types I and II. Argina se I is a component of the urea cycle, and inherited defects in arginase I have deleterious consequences in humans. In contrast, the physiologic role of arginase II has not been defined, and no deficiencies in arginase II hav e been identified in humans. Mice with a disruption in the arginase II gene were created to investigate the role of this enzyme. Homozygous arginase I I-deficient mice were viable and apparently indistinguishable from wild-typ e mice, except for an elevated plasma arginine level which indicates that a rginase II plays an important role in arginine homeostasis.