UniTmp is a unified platform that merges TOPDB, TOPDOM, PDBTM and HTP databases and provides interoperability between the incorporated resources. The current update contains 9,235 membrane-embedded structures, 9,088 sequences with 536,035 topology-annotated segments, and 8,692 conservatively localized protein domains or motifs as well as 5,466 annotated human transmembrane proteins.