Enables the transfer of transition metal ions from one side of a membrane to the other. A transition metal is an element whose atom has an incomplete d-subshell of extranuclear electrons, or which gives rise to a cation or cations with an incomplete d-subshell. Transition metals often have more than one valency state. Biologically relevant transition metals include vanadium, manganese, iron, copper, cobalt, nickel, molybdenum and silver. [ https://www.worldcat.org/search?q=bn%3A0198506732 ]