Before revision:  The stem-loop tertiary interactions rupture first followed by unfolding of the 3^{\prime}-end hairpin (\textrm{ U-I } \textrm{ ).
After revision:  The stem-loop tertiary interactions rupture first followed by unfolding of the 3^{\prime}-end hairpin (\textrm{ U-I } \rightleftharpoons\textrm{ ).