Regulatory Differences among Avian Ecto-ATPases

Extracellular ATP is found to produce a variety of important biological responses. Ecto-ATPases are located on numerous cell types in many different species, regulate extracellular ATP levels and can be a key step 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 Km's, (2) lectin sensitivity, (3) responses to detergents, (4) responses to lipid mediators, and (5) responsiveness to nucleotide-mimetic affinity labels. These results suggest that although each enzyme hydrolyzes extracellular ATP, they should each be viewed as a distinct subtype of the whole ecto-ATPase family due to their differential responses, largely linked to proposed regulatory phenomenon.