obsolete lactone transmembrane transporter activity (obsolete GO:0042971)
OBSOLETE. Enables the transfer of lactone from one side of a membrane to the other. A lactone is a cyclic ester of a hydroxy carboxylic acid, containing a 1-oxacycloalkan-2-one structure, or an analogue having unsaturation or heteroatoms replacing one or more carbon atoms of the ring.