We report that the fission yeast nucleoporin Nup124p is required for the nuclear 
import of both, retrotransposon Tf1-Gag as well as the retroviral HIV-1 Vpr. 
Failure to import Tf1-Gag into the nucleus in a nup124 null mutant resulted in 
complete loss of Tf1 transposition. Similarly, nuclear import of HIV-1 Vpr was 
impaired in nup124 null mutant strains and cells became resistant to Vpr's 
cell-killing activity. On the basis of protein domain similarity, the human 
nucleoporin Nup153 was identified as a putative homolog of Nup124p. We 
demonstrate that in vitro-translated Nup124p and Nup153 coimmunoprecipitate 
Tf1-Gag or HIV-1 Vpr. Though full-length Nup153 was unable to complement the Tf1 
transposition defect in a nup124 null mutant, we provide evidence that both 
nucleoporins share a unique N-terminal domain, Nup124p(AA264-454) and 
Nup153(AA448-634) that is absolutely essential for Tf1 transposition. Epigenetic 
overexpression of this domain in a wild-type (nup124(+)) background blocked Tf1 
activity implying that sequences from Nup124p and the human Nup153 challenged 
the same pathway affecting Tf1 transposition. Our results establish a unique 
relationship between two analogous nucleoporins Nup124p and Nup153 wherein the 
function of a common domain in retrotransposition is conserved.