FIG. 1.

(A) Organization of the gypsy element. Two LTRs flank a central region which contains the three ORFs corresponding to gag, pol, and env. The order of the various domains of the pol gene is indicated (PR, protease; RT, reverse transcriptase; RH, RNase H; IN, integrase). The predicted 54-kDa protein encoded by ORF3 is represented with potential N-glycosylation sites (Y), the signal peptide (SP), the dibasic cleavage site (arrow), and the transmembrane domain (TM). (B) Genetic organization of pHCMV-gyp-ENV. Numbers refer to gypsy nucleotides. CMV, human cytomegalovirus immediate-early promoter; SPL and PA, splicing and polyadenylation signals, respectively, derived from the rabbit beta-globin gene.