Enables the transfer of a solute from one side of a membrane to the other, up its concentration gradient. The transporter binds the solute and undergoes a series of conformational changes. Transport works equally well in either direction and is driven by a chemiosmotic source of energy, not direct ATP coupling. Secondary active transporters include symporters and antiporters. [ http://www.ncbi.nlm.nih.gov/pubmed/10839820 https://www.worldcat.org/search?q=bn%3A0815340729 https://www.worldcat.org/search?q=bn%3A0198506732 ]