Tissue transglutaminase is a multifunctional enzyme which has been involved
in the regulation of cell growth, differentiation, and apoptosis, Recently
, nuclear localization of tTG has been reported indicating the potential of
active nuclear transport, In this study we use the yeast two-hybrid assay
and coimmunoprecipitation to show that tTG interacts with the nuclear trans
port protein importin-alpha 3. Using electron microscopy we demonstrate tha
t nuclear expression of tTG in a non-small cell lung cancer cell line is in
duced by retinoic acid (RA), These data suggest that importin-alpha 3 could
mediate active nuclear transport of tTG which may be important for the reg
ulation of critical cellular processes. (C) 1999 Federation of European Bio
chemical Societies.