transporter activity transmembrane transporter activity Enables the transfer of a substance from one side of a membrane to the other. GO:0005386 GO:0015646 GO:0022857 Reactome:REACT_100033 Reactome:REACT_106735 Reactome:REACT_111088 Reactome:REACT_111933 Reactome:REACT_113047 Reactome:REACT_113116 Reactome:REACT_113829 Reactome:REACT_114161 Reactome:REACT_19288 Reactome:REACT_77235 Reactome:REACT_81225 Reactome:REACT_88503 Reactome:REACT_91849 Reactome:REACT_94185 molecular_function