May play a role in the regulation of extra-urea cycle arginine metabolism and also in down-regulation of nitric oxide synthesis. Extrahepatic arginase functions to regulate L-arginine bioavailability to nitric oxid synthase (NOS). Arginine metabolism is a critical regulator of innate and adaptive immune responses. Seems to be involved in negative regulation of the survival capacity of activated T cells. May suppress inflammation-related signaling in asthmatic airway epithelium. May play a role in promoting prenatal immune suppression. Regulates RPS6KB1 signaling, which promotes endothelial cell senescence and inflammation and implicates NOS3/eNOS dysfunction. Can inhibit endothelial autophagy independently of its enzymatic activity implicating mTORC2 signaling. Involved in vascular smooth muscle cell senescence and apoptosis independently of its enzymatic activity. H2O + L-arginine = L-ornithine + urea Binds 2 manganese ions per subunit. Nitrogen metabolism; urea cycle; L-ornithine and urea from L-arginine: step 1/1. Homotrimer. Belongs to the arginase family.