REGULATORY DIFFERENCES AMONG AVIAN ECTO-ATPASES

Extracellular ATP is found to produce a variety of important biologica l responses. Ecto-ATPases are located on numerous cell types in many d ifferent species, regulate extracellular ATP levels and can be a key s tep in generating adenosine, Studies conducted on chicken ecto-ATPases from liver and cardiac and smooth muscle show a variety of differing properties including (1) different apparent K-m's, (2) lectin sensitiv ity, (3) responses to detergents, (4) responses to lipid mediators, an d (5) responsiveness to nucleotide-mimetic affinity labels. These resu lts suggest; that although each enzyme hydrolyzes extracellular ATP, t hey should each be viewed as a distinct subtype of the whole ecto-ATPa se family due to their differential responses, largely linked to propo sed regulatory phenomenon. (C) 1997 Academic Press.