Sucrose transport

Wyse, R.E., Zamski, E. Tomos, A.D. (1986). Turgor regulation of sucrose transport in sugar beet tap root tissue. Plant Physiology, 81, 478-81. 

The in vitro system we have been using to study the transepithelial transport is cultured Madin-Darby canine kidney (MDCK) epithelial cells (11). When cultured on microporous polycarbonate filters (Transwell, Costar, Cambridge, MA), MDCK cells will develop into monolayers mimicking the mucosal epithelium (11). When these cells reach confluence, tight junctions will be established between the cells, and free diffusion of solutes across the cell monolayer will be markedly inhibited. Tight junction formation can be monitored by measuring the transepithelial electrical resistance (TEER) across the cell monolayers. In Figure 1, MDCK cells were seeded at 2 X 104 cells per well in Transwells (0.4 p pore size) as described previously. TEER and 14C-sucrose transport were measured daily. To determine 14C-sucrose... 

In E. coli, lactose is taken up by means of proton symport, maltose by means of a binding (ABC-type) protein-dependent system, melibiose by means of Na+ symport, and glucose by means of the phosphotransferase system (PTS). Although this bacterium normally does not transport sucrose, suppose that you isolated a strain that does. How do you determine whether one of the four mechanisms just listed is responsible for sucrose transport in this mutant strain ... 

Barth I, Meyer S, Sauer N. 2003. PmSUC3 Characterization of a SUT2/SUC3-type sucrose transporter from Plantago major. Plant Cell 15 1375-1385. 

Eckardt NA. 2003. The function of SUT2/SUC3 sucrose transporters. The debate continues. Plant Cell 15 1259-1262. 

S. Delrot, N. Roques, G. Descotes, and J. Mentech, Recognition of some deoxy derivatives of sucrose by the sucrose transporter of the plant plasma membrane, Plant Physiol. Biochem., 29 (1991) 25-29. 

Kuhn, C., Quick, W.P., Schulz, A., Riesmeier, J.W., Sommewald, U., and Frommer, W.B., Companion cell-specific inhibition of the potato sucrose transporter SUT1, Plant Cell Environ., 19, 1115-1123, 1996. 

Foreign enzymes—that is, with no plant equivalent, have been introduced into plants one of the uses of this approach was to address the nature of sucrose transport into the phloem. An invertase derived from the yeast enzyme was targetted to the cell wall of tobacco, potato, tomato, and A. thaliana (Sonnewald et al., 1994). The introduction of invertase decreased yield, presumably through the inhibition of sucrose transport. 

The chloroplast is encircled by a double membrane called the envelope. Of the two membranes, the inner is practically impermeable to hydrophylic compounds, such as Pj, phosphate esters, dicarboxylates, glucose and sucrose. Transport of certain of these metabolites is accomplished by carrier proteins, specific for groups of compounds. Individual carriers have been shown to facilitate the transport of Pj and phosphate esters, dicarboxylates, ATP and ADP, and glucose. >... 

Sucrose from photosynthetic cells Is transported through the phloem to nonphotosynthetIc parts of the plant. Osmotic pressure differences provide the force that drives sucrose transport (see Figure 8-45). 

Sucrose Transport in Plants Using Monofluorinated Sucroses and Glucosides... 

Transmembrane movement of sucrose is accomplished by transport proteins in several, but not all tissue types. The most obvious example of a specific tissue type is the phloem. The sucrose concentration in this tissue can approach 0.8 M in contrast to mM concentration in the surrounding tissues and probably sub mM concentration in the extra cellular spaces surrounding the phloem (2). Transport into the cells of the phloem is difficult to study as they are an integral part of the leaf or stem structure, and may comprise only 5 to 10% of the total leaf mass. Another example of sucrose transport is the accumulation of sucrose and other nutrients by cells of... 

Knop, C., Voitsekhovskaja, O., and Lohaus, G., Sucrose transporters in two members of the Scrophulariaceae with different types of transport sugar, Planta, 213, 80, 2001. 

AOKl, N., HIROSE, T., SCOFIELD, G.N., WHITFELD, P.R., FURBANK, R.T., The sucrose transporter gene family in rice. Plant Cell Physiol., 2003,44,223-32. 

Baud, S. Wuilleme, S. Lemoine, R. Kronenberger, J. Caboche, M. Lepiniec, L. Rochat, C. (2005). The AtSUCS sucrose transporter specifically expressed in the endosperm is involved in early seed development in Arabidopsis. Plant Journal, Vol.43, No.6, (September 2005), pp. 824-836, ISSN 0%0-7412... 

Sucrose transport to and utilization by legume nodules is required for effective N2 fixation and ammonia assimilation (Schubert, 1986 Streeter and Sal-minen, 1985). Sucrose metabolism is mediated by sucrose synthase (SS). Sucrose synthase activity is high in soybean nodules (Morell and Copeland, 1985). The enzyme has been purified from soybean nodules and appears to be a tetramer made up of 90- to 100-kDa subunits. 

Thus, as might be expected of a compound of such importance as sucrose, its metabolism is complex and at least three distinct enzyme systems are involved in its synthesis and breakdown. Furthermore, isozymes of invertase have been described which reside in different parts of the cell and which may be associated with the control of sucrose transport and utilization. It is clear that we must await further information before the inter-relationships between the several pathways of sucrose metaboUsm can be fully clarified. 

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