FIG. 1.

The Ty5 TD is located at the C terminus of integrase. (A) Ty5 is 5,375 bp in length. It expresses a full-length protein of 182 kDa, which is processed by protease (PR) into Gag, IN, and RT (22). The cleavage sites, based on the mobilities of mature proteins by SDS-PAGE, are shown by dashed lines. The black bar marks the position of TD. The BspEI and PflMI sites define the region of IN used in the mutagenesis experiment. pIP19, pWW32, and pWW59 carry Ty5 elements that were modified by an RGS-H₆ tag. The tag replaced TD (pWW59) or was inserted either into the middle of IN (pWW32) or at the end of RT (pIP19) (22). (B) The modified Ty5 elements were expressed in yeast, and an anti-RGS-H₆ antibody was used to identify IN or RT on immunoblots. The partially processed and mature protein species are indicated. (C) The Ty5 IN fragments used throughout this paper are shown. INC and inc are 258 aa long (the small letters indicate the version with the S1094L mutation). TD and td represent the wild-type and mutant TD plus 3 flanking aa from Ty5. (D) Western blots demonstrating that the wild-type and mutant GBD fusion proteins are expressed at comparable levels in the test strains (YSB2 and UCC3505). GBD-INC and GBD-TD have molecular masses of approximately 47 and 19 kDa, respectively.