AT P





 bB,
 arg3 64ile-V5 '
 arg3 64glu-V5















 bwt-his
 bw~t-h is/ba rg3 seale-vS
 wthis~ arg364glu-V5
 bwt-his/b,_y,



 2 min bwt y,
 byt

Figure 3-3. ATP-driven energization of membrane vesicles prepared from uncF(b) arg36
 gene mutants. Membrane vesicles were prepared by differential
 centrifugation. Membrane protein (200 Gig) was suspended in 3 ml of assay
 buffer (50 mM MOPS, 10 mM MgCl2, pH 7.3). The fluorescent dye ACMA
 was added to a final concentration of 1 C1M, and fluorescence was recorded
 with excitation at 410 nm and emission at 490 nm. ATP was added as
 indicated to a final concentration of 1mM. The samples for each trace have
 been labeled according to the b subunit mutation and the epitope tag, so the
 strains used as the sources of the samples were as follows: Ab, KM2/pBR322;
 bwt, KM2/pKAM14; b,,.-vs, KM2/pTAM46; bwt-his, KM2/pTAM37; barg364ile-
 vs, KM2/pTAM53; barg364glu-15, KM2/pTAM54; birthis/b~~s,.x,
 KM2/pTAM37/pTAM46; but-his/barg36,ile-15, KM2/pTAM37/pTAM53; b,,4
 his/barg364glu-1 5, KM2/ p TAM37/p TAM54.