<p>Synonyms: mevalonate diphosphate decarboxylase; pyrophosphomevalonate decarboxylase.</p><p>This group of enzymes belongs to the GHMP kinase domain superfamily. GHMP kinases are a unique class of ATP-dependent enzymes (the abbreviation of which refers to the original members: galactokinase, homoserine kinase, mevalonate kinase, and phosphomevalonate kinase) [<cite idref="PUB00015675"/>]. Enzymes belonging to this superfamily contain three well-conserved motifs, the second of which has the typical sequence Pro-X-X-X-Gly-Leu-X-Ser-Ser-Ala and is involved in ATP binding [<cite idref="PUB00015644"/>]. The phosphate binding loop in GHMP kinases is distinct from the classical P-loops found in many ATP/GTP binding proteins. The bound ADP molecule adopts a rare syn conformation and is in the opposite orientation from those bound to the P-loop-containing proteins [<cite idref="PUB00015644"/>]. GHMP kinases display a distinctly bilobal appearance with their N-terminal subdomains dominated by a mixed beta-sheet flanked on one side by alpha-helices and their C-terminal subdomains containing a four stranded anti-parallel beta-sheet [<cite idref="PUB00015835"/>, <cite idref="PUB00015644"/>, <cite idref="PUB00015669"/>, <cite idref="PUB00015730"/>]. </p><p>Diphosphomevalonate decarboxylase (mevalonate pyrophosphate decarboxylase, (<db_xref db="EC" dbkey="4.1.1.33"/>) catalyzes the decarboxylation of mevalonate pyrophosphate to isopentyl pyrophosphate (IPP) [<cite idref="PUB00016172"/>], the last step in the synthesis of IPP in the mevalonate pathway. Mevalonate is a key intermediate in the biosynthesis of sterols and non-sterol isoprenes in the mevalonate pathway. In mammals, the majority of mevalonate is converted into cholesterol.<reaction> ATP + (R)-5-diphosphomevalonate = ADP + phosphate + isopentenyl diphosphate + CO2 </reaction> </p>