Immunocytolocalization of plasma-membrane H(+)-ATPase in maize coleoptiles and enclosed leaves

The plasma-membrane H(+)-ATPase (EC 3.6.1.35) of maize (Zea mays L.) coleoptiles and enclosed leaves has been localized at the optical-microscope level utilizing paraffin sections and a specific monoclonal antibody. Both in coleoptiles and in leaves the stomatal guard cells and the phloem of vascular bundles are the tissues most enriched in ATPase. The enrichment in guard cells is relevant to active ion transport during stomata opening. Considering the postulated activation of coleoptile ATPase by auxin, it is remarkable that the ATPase is not enriched in the coleoptile epidermis, where most of the auxin receptor is located.