Immunolocalization of proton-ATPase in the gills of the elasmobranch,Squalus acanthias

Proton-ATPase was localized to mitochondria-rich cells in the interlamellar region of the gills of the elasmobranch, Squalus acanthias. Localization was accomplished using a polyclonal antibody specific for the 70 kDa subunit of the (V-type) proton-ATPase as confirmed by Western blot analysis. In addition, significant levels of N-ethymaleimide sensitive ATPase activity (0.116 +/- 0.026 mumol Pi.mg-1 protein.h-1) were also measured in crude gill membrane preparations. These data provide, for the first time, direct evidence of the localization of elements possibly involved in branchial acid-base (or ionic) regulation in elasmobranchs.