Hepatitis B virus PRE alpha

The Hepatitis B virus PRE stem-loop alpha (HBV PRE SL alpha) is an RNA structure that is shown to play a role in nuclear export of HBV mRNAs.
HBV PREalpha consists of a 30 nt stem-loop, with a 5 nt apical loop. The conserved stem-loop was predicted within the HBV PRE sequence and confirmed by mutagenesis.
The exact role of this structure in nuclear export has not yet been determined.