A 100-kDa antigen recognized by a newly prepared monoclonal antibody specific to the vanadocytes of the vanadium-rich ascidian, Ascidia sydneiensis samea, is glycogen phosphorylase

Abstract

Ascidians have the unusual physiological ability to accumulate high levels of vanadium and reduce it to the +3 oxidation state (VIII) in vanadocytes, the vanadium-containing blood cells. We are characterizing several polypeptides specific to vanadocytes that may participate in this. This study revealed that a 100-kDa antigen, recognized by a newly prepared monoclonal antibody, S8E4, is exclusively localized in vanadocytes, and identified the antigen as glycogen phosphorylase (EC 2.4.1.1) by sequencing the encoded cDNA. Since two enzymes, glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44), both in the pentose phosphate pathway, have already been identified in vanadocytes, at least three enzymes involved in carbohydrate metabolism are localized in vanadocytes in huge amounts.