cORF and RcRE, the Rev/Rex and RRE/RxRE homologues of the human endogenous retrovirus family HTDV/HERV-K

J Virol. 1999 Nov;73(11):9496-507. doi: 10.1128/JVI.73.11.9496-9507.1999.


cORF, a protein encoded by the human endogenous retrovirus family HTDV/HERV-K, contains amino acid motifs which resemble the nuclear import and export signals of the viral regulatory proteins Rev (human immunodeficiency virus) and Rex (human T-cell leukemia virus [HTLV]). In this study, we demonstrated that cORF indeed has a Rev-like function and mapped the cORF-responsive RNA element to a sequence in the 3' long terminal repeat, a localization similar to RxRE, the responsive element in HTLV type 1. Accordingly, we have given the element the designation RcRE. cORF and RcRE stabilize unspliced and incompletely spliced viral transcripts and enhance their nuclear export via the CRM1 export pathway. So far, HTDV/HERV-K is the only endogenous retrovirus family with a complex regulation at the posttranscriptional level. It may be regarded as an intermediate in the evolution from simple to complex retroviruses.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • COS Cells
  • Carrier Proteins / metabolism
  • Endogenous Retroviruses / genetics*
  • Endogenous Retroviruses / metabolism
  • Gene Expression Regulation, Viral
  • Gene Products, gag / metabolism
  • Gene Products, rev / genetics*
  • Gene Products, rev / metabolism
  • Gene Products, rex / genetics*
  • Gene Products, rex / metabolism
  • Humans
  • Immunoblotting
  • Immunohistochemistry
  • Karyopherins*
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Open Reading Frames / genetics*
  • Plasmids
  • RNA Splicing
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Viral / genetics
  • RNA, Viral / metabolism
  • Receptors, Cytoplasmic and Nuclear*
  • Response Elements*
  • Transcription, Genetic
  • Transfection
  • Tumor Cells, Cultured


  • Carrier Proteins
  • Gene Products, gag
  • Gene Products, rev
  • Gene Products, rex
  • Karyopherins
  • RNA, Messenger
  • RNA, Viral
  • Receptors, Cytoplasmic and Nuclear
  • exportin 1 protein