Group translocators

The bacterial phosphoenolpyruvate (PEP)-dependent carbohydrate phosphotransferase systems (PTS) are characterised by their unique mechanism of group translocation. The transported solute is chemically modified (i.e. phos-phorylated) during the process (for comprehensive reviews see [151,152] and... 

Figure 6. Uptake of various sugars via the phosphoenolpyruvate group translocator (PTS) mechanism. Please note that all systems shown share the common components El and HPr. For details see the text...

The following are recent reviews on the molecular and physical properties of this transferase involved in group translocation. 

Yarbrough, J. M., Rake, J. B., and Eagon, R. G. (1980). Bacterial inhibitory effects of nitrite Inhibition of active transport, but not of group translocation, and of intracellular enzymes. Appl. Environ. Microbiol. 39, 831-834. 

One kind of active transport, namely group translocation, occurs in bacteria (for reviews, see Refs. 218-223), and some workers consider that this also takes place in yeasts (see, for example, Refs. 224 and 225) by this means, uptake of a sugar is directly coupled to its phosphorylation, and the sugar is released into the cytoplasm as a phosphate. 

Alternatively, both the first and the second solutes may pass through the membrane bound to the same carrier (cotransport or symport). Another form of active transport is group translocation, a process in which the substance to be transported undergoes covalent modification, e.g., by phosphorylation. Tire modified product enters the cell and within the cell may be converted back to the unmodified substance. Transport processes, whether facilitated or active, often require the participation of more than one membrane protein. Sometimes the name permease is used to describe the protein complexes utilized. 

Group translocation 411 Growth, control of 578 Growth factors 571-576,722 Growth rates of cells 470 Growth regulating hormones 567- 571 GTP (guanosine triphosphate) as coenzyme 719... 

Glucose ATP out—A DP in H+ Na+ out—K+ in Glucose Glucose Facilitated diffusion Facilitated diffusion Primary active (uses ATP) Primary active (uses ATP) Secondary active (Na+ cotransport) Group translocation Most animal cells Mitochondria Stomach epithelia Animal cells Some animal cells Many bacteria... 

In the bacterium E. coli, glucose is taken up by group translocation, lactose is taken up by secondary active transport (using H + ), and maltose is taken up by means of a binding-protein system. Outline how it would be possible to determine whether melibiose (a disaccharide of glucose and galactose) is taken up by . coli and. if it is, whether one of the mechanisms described earlier applies. 

Unlike hypoxanthin-l-ol, xanthin-l-ol is precluded from N1 to C2 oxygen transition, but instead undergoes an N1 to N3 hydroxy group translocation. ... 

Group translocation refers to which of the following processes ... 

A third kind of sugar-uptake system occurs in bacteria (for reviews, see Refs. 158-162), namely group translocation, and some authorities consider that this occurs in yeasts, too.163 In certain bacteria, uptake of sugar is coupled to its phosphorylation and to energy-yielding metabolism it involves the following overall reaction. 

Group translocators Group of carriers that alter the solute during its passage across the membrane in a vectorial enzyme reaction. 

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