Galactose permease

S. typhimurium normally transport trehalose via the galactose permease and are able to grow on this substrate in the complete absence of PTS phosphorylating activity. However, in S. typhimurium which lack a functional galactose permease, IfMan appears to be able to transport trehalose [78]. There is no evidence that trehalose is phosphorylated in this process, again pointing to Il "-dependent transport in the facilitated diffusion mode. 

In the induction of enzymes of galactose metabolism in E. coli, three enzymes are involved -galactosidase (which catalyses the hydrolysis of the y -glycosidic bonds of lactose), galactose permease (which is responsible for transport of lactose across the cell membrane) and a third enzyme, A-protein, apparently not directly involved in galactose metabolism. The system has an environmental inducer, galactose, and in its presence the number of /)-galactosidase molecules rises from 5-10 to 10,000 within the cell. The addition of the inducer can increase the protein production in less than five minutes after its addition. Protein synthesis of these enzymes stops almost immediately in the absence of lactose. 

GAF2 Galactose permease, required for utilization of galactose also able to transport glucose... 

Galactose permease (M protein) activity abolished, blocking lactose utilization... 

A.2.2.3 Galactose permease GalP Lact. lactis Grossiord et al. 2003... 

Guan, L., Sahin-Toth, M. and Kaback, H. R. (2002). Changing the lactose permease of Escherichia coli into a galactose-specific symporter, Proc. Natl Acad. Sci. USA, 99, 6613-6618. 

A particularly well-studied example of a simple subsystem in evolutionary research is utilization of lactose, which consists of three essential components (i) porin-mediated diffusion through the cell wall, (ii) active uptake via a permease, and (iii) intracellular hydrolysis into glucose and galactose by /3-galactosidase. Assuming that central metabolism will utilize these cleavage products, the lac-... 

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