Catalyzes the ATP dependent decarboxylation of (R)-5-diphosphomevalonate to form isopentenyl diphosphate (IPP). Functions in the mevalonate (MVA) pathway leading to isopentenyl diphosphate (IPP), a key precursor for the biosynthesis of isoprenoids and sterol synthesis. (R)-5-diphosphomevalonate + ATP = ADP + CO2 + isopentenyl diphosphate + phosphate Steroid biosynthesis; cholesterol biosynthesis. Homodimer. Expressed in heart, skeletal muscle, lung, liver, brain, pancreas, kidney and placenta. The disease is caused by variants affecting the gene represented in this entry. Belongs to the diphosphomevalonate decarboxylase family. Was originally thought to be located in the peroxisome (PubMed:11108725). However, was later shown to be cytosolic (PubMed:14972328).