Tap, RNA-binding <p>This domain adopts a structure consisting of an alpha+beta sandwich with an antiparallel beta-sheet, arranged in a 2(beta-alpha-beta) motif. They are mainly found in mRNA export factors, and mediate the sequence nonspecific nuclear export of cellular mRNAs as well as the sequence-specific export of retroviral mRNAs bearing the constitutive transport element [<cite idref="PUB00026786"/>]. </p>