Lysosome .
Isoform PDE1C2 is present in the heart and brain and, at lower levels in the lung, liver, kidney and skeletal muscle (PubMed:8557689). Isoform PDE1C1 is expressed in the heart and brain and, at lower levels in lung (PubMed:8557689). Also expressed at low levels in uterus and testis (PubMed:8557689).