New insights into molecular structure and function of ectonucleotidases in the nervous system.

Nucleotides can be released as signaling substances in the nervous system from both neural and glial cells. Their function is terminated by ecto-nucleotidases and sequential extracellular metabolism to the nucleoside. Recently considerable progress has been made in unraveling the molecular structure of an ecto-ATPase and an ecto-ATP diphosphohydrolase, two closely related ectoenzymes. Molecular structure, tissue distribution and functional properties of the ecto-nucleotidases are discussed with particular emphasis on the nervous system.