(R)-5-phosphomevalonate + ATP = (R)-5-diphosphomevalonate + ADP kcat is 20.9 sec(-1) with (R)-5-phosphomevalonate. Isoprenoid biosynthesis; isopentenyl diphosphate biosynthesis via mevalonate pathway; isopentenyl diphosphate from (R)-mevalonate: step 2/3. Belongs to the GHMP kinase family. Mevalonate kinase subfamily.