Relationship of the vav-hCD4 transgenes to thevav locus. (A) 5′ end of the mouse vav locus showing the 5 hematopoietic-specific HS sites (▿) surrounding exon 1 (▪), as well as a testis-specific promoter (t) near exon 2 (see Discussion). (B) Expanded map of the vav regions used in the transgenes, with the untranslated portion of exon 1 shown unfilled. (C) The HS321/45 vav-hCD4 transgene. (D) The HS21/45 transgene, showing 2 PCR primers (a and b) used in its construction (see Materials and Methods). (E) The mutant hCD4 protein from which the reporter was derived. ss, splice sites; pA, polyadenylation region F43I, the mutated extracellular residue; TM, transmembrane region. Restriction sites are K, Kpn I; R,EcoRI; B, BamHI; S2, Sac II; N, Nco I; Ne, Nae I; Hp, Hpa I; H3, HindIII; those in parentheses have been destroyed, whereas those in bold were used to excise the transgenes from the plasmid backbone; for more detailed maps, see Ogilvy et al.11