|Budget Amount *help
¥2,300,000 (Direct Cost : ¥2,300,000)
Fiscal Year 1998 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1997 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1996 : ¥900,000 (Direct Cost : ¥900,000)
Phosphagen (guanidino) kinases constitute a family of highly conserved enzymes which catalyze the reversible transfer of phosphate from phosphagen (creatine phosphate (CP), arginine phosphate (AP), glycocyamine phosphate (GP), lombricine phosphate (LP), taurocyamine phosphate (TP), hypotaurocyamine phosphate (HTP)) to ADP yielding ATP.Creatine kinase (CK), the most widely studied member of this family, plays a central role in both temporal and spatial ATP buffering in cells which display high and variable rates of energy turnover. The remaining major members of this family (arginine kinase (AK), glycocyamine kinase (GK), lombricine kinase (LK), taurocyamine kinase (TK), hypotaurocyamine kinase (HTK)) have not been investigated as extensively as CK but likely play a similar physiological role.
In order to make clear the molecular evolution in this family, we have determined the cDNA-derived amino acid sequences of two molluscan arginine kinases from the chiton Liolophura japonica and the
turbanshell Battilus cornutus, of two unusual two-domain arginine kinases from the sea anemone Anthopleura japonicus and the clam Pseudocardium sachalinensis, of lombricine kinase from the earthworm Eisenia foetida, and of glycocyamine kinase from the polychaete Neanthes diversicolor.
In the functional and evolutionary studies of phosphagen kinases, of special interest is the question of which residues are associated with the recognition of the different substrates, creatine, glycocyamine, arginine and lombricine. From an amino acid sequence alignment of CKs, GK, LK and AKs, we proposed that a region displaying remarkable amino acid deletions (referred to GS region), as a possible candidate for guanidine substrate recognition site. Clearly, there is a proportional relationship between the size of the deletion in GS region and the mass of guanidine substrate used. Namely, LK and AK that use relatively large guanidine substrates, lombricine and arginine, have a 5-amino acid deletion in this region, CK has one-amino acid deletion, and GK has no deletion. Less