FIG. 1.

(A) ORF1p tagged on the C terminus with enhanced GFP is predominantly cytoplasmic but is also present in nuclei and nucleoli of some cells. (B) GFP-tagged ORF1p from the fish retrotransposon SW1 is cytoplasmic with punctate foci in human 143Btk- cells. Nucleolar localization of this protein was not observed. (C) Phylogenetic alignment of internal sequence from ORF1p and the location of point mutations. Mutations were also introduced into a retrotransposition-competent L1 (L1-RP) and tested in a cell culture retrotransposition assay. Retrotransposition rates were compared with that of wild-type L1-RP (right).