
This domain identifies a group of enzymes belongs to the GHMP kinase domain superfamily in the archaea . 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 ) [ 1 ] . 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 [ 2 ] . 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 [ 2 ] . 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 [ 3 , 2 , 4 , 5 ] . There are currently no experimental data for members of this family , and their exact biochemical and biological functions are not known yet .