1Department of Biochemistry, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK.
2Department of General Zoology, Lorand Eotvos University, Budapest H-1088, Hungary.
3Department of Biochemistry, University of Nottingham Medical School, Queen's Medical Centre, Nottingham NG7 2UH, UK and Department of General Zoology, Lorand Eotvos University, Budapest H-1088, Hungary.