P-type ATPase diversity and evolution: The origins of ouabain sensitivity and subunit assembly

Molecular aspects of the diversity of P-type ATPases are explored in this r eview From the substrate specificities among different ATPase molecules, th e existence of isoforms within a single class of pump becomes evident and i t is now recognized as a universal phenomenon. From the phylogenetic analys es using a vast collection of the deduced amino acid sequences for the P-ty pe ATPase subunits, it also becomes evident that the divergence of substrat e-specificity occurred early in the evolution and has been conserved ever s ince. Further extensive analyses identify a set of novel isoforms that reta in an ancestral characteristic of the Na+/K+-(H+/K+-)ATPases in invertebrat es.