Multiple tRNA attachment sites in prothymosin alpha

A covalent complex formed by bacterial tRNAs and prothymosin alpha, an abun dant acidic nuclear protein involved in proliferation of mammalian cells, u pon production of the recombinant rat protein in Escherichia coli cells was studied. Several tRNA attachment sites were identified in the prothymosin alpha molecule using a combination of deletion analysis of prothymosin alph a and site-specific fragmentation of the protein moiety of the prothymosin alpha-tRNA complex. The electrophoretic mobilities of the tRNA-linked proth ymosin alpha and its derivatives are consistent with one tRNA molecule atta ched to one prothymosin a molecule, thus suggesting that alternative tRNA l inking to one of several available attachment sites occurs. The possible ef fect of tRNA attachment on the nuclear uptake of prothymosin alpha is discu ssed. (C) 1999 Federation of European Biochemical Societies.