2015 August 26, “Mutations in the DI-DII Linker of Human Parainfluenza Virus Type 3 Fusion Protein Result in Diminished Fusion Activity”, in PLOS ONE, →DOI:
Fig 1B shows the localization of this linker (residues 369–374) in the 3-D structure of the HPIV3 F protein in the prefusogenic conformation.