DIVERGENT SUBCELLULAR LOCATIONS OF HTLV-I TAX AND INT-6 - A CONTRAST BETWEEN IN-VITRO PROTEIN-PROTEIN BINDING AND INTRACELLULAR PROTEIN COLOCALIZATION

Protein-protein interactions define many important molecular and cellu lar processes in prokaryotic and eukaryotic biology. In trying to deli neate the contact between two proteins, the yeast two-hybrid assay has emerged as a powerful technique. Complementing the yeast two-hybrid a ssay are in vitro techniques (e.g. GST-fusion-protein chromatography) that can also yield information on protein-protein associations. Howev er, unambiguous functional significance to these interactions is best supported through a finding of colocalization of two proteins inside c ells. In instances where two proteins interact in vitro but have diver gent localizations within cells one needs to reconsider the biological importance of the former finding. Here, we present evidence for diffe rent subcellular locations of HTLV-I Tax and the Int-6 protein. We sug gest a reexploration of the functional significance between Tax and In t-6 in cellular transformation.