Tissue distribution of ecto-Mg-ATPase in adult and embryonic chicken

We have determined the distribution of chicken ecto-Mg-ATPase in a variety of tissues from adult and embryonic chicken. The presence of ecto-Mg-ATPase was identified by an antibody raised against a 12 amino acid residue peptide, NH2-KILSGEEEGVFG, derived from proteolysis and sequencing of the chicken gizzard ecto-Mg-ATPase. Adult chicken tissues were also assayed for ATPase activity in the presence/absence of stimulators/inhibitors of the ecto-ATPase in order to confirm the immunologic tissue distribution results. There is controversy in the literature as to the size(s) of ecto-Mg-ATPases. We demonstrate here that the apparent size of the enzyme(s) recognized by anti-peptide antibodies by Western blot analysis depends on the denaturation conditions used prior to electrophoresis. Lastly, we deduce that the chicken ecto-ATPase is not identical to T-cadherin, as has been recently proposed.