The function of UPB1 (beta-ureidopropionase 1, ENSG00000100024) is as follows. Catalyzes a late step in pyrimidine degradation (PubMed:22525402, PubMed:24526388). Converts N-carbamoyl-beta-alanine (3-ureidopropanoate) into beta-alanine, ammonia and carbon dioxide (PubMed:10415095, PubMed:10542323, PubMed:11508704, PubMed:22525402, PubMed:24526388, PubMed:29976570). Likewise, converts N-carbamoyl-beta- aminoisobutyrate (3-ureidoisobutyrate) into beta-aminoisobutyrate, ammonia and carbon dioxide (Probable). {ECO:0000269|PubMed:10415095, ECO:0000269|PubMed:10542323, ECO:0000269|PubMed:11508704, ECO:0000269|PubMed:22525402, ECO:0000269|PubMed:24526388, ECO:0000269|PubMed:29976570, ECO:0000305|PubMed:22525402, ECO:0000305|PubMed:24526388}.