Lee J I, Okazaki N, Tsuchiya T, Wilson T H
Department of Cell Biology, Harvard Medical School, Boston, MA 02115.
Biochem Biophys Res Commun. 1994 Sep 30;203(3):1882-8. doi: 10.1006/bbrc.1994.2407.
The gene coding for the lactose carrier of Citrobacter freundii was cloned into the plasmid pBR322. The gene was sequenced and the amino acid sequence was found to be 70% identical to the lactose carrier of E. coli. All of the charged residues in the membrane spanning region were conserved. The sugar specificity is somewhat different from that of E. coli. The C. freundii carrier has less activity for lactose and more activity for o-nitrophenyl-galactose (ONPG) than the carrier of E. coli.
弗氏柠檬酸杆菌乳糖载体的编码基因被克隆到质粒pBR322中。对该基因进行了测序，发现其氨基酸序列与大肠杆菌的乳糖载体有70%的同源性。跨膜区域的所有带电残基都是保守的。其糖特异性与大肠杆菌的有所不同。与大肠杆菌的载体相比，弗氏柠檬酸杆菌载体对乳糖的活性较低，而对邻硝基苯基半乳糖（ONPG）的活性较高。
