Access

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If You Use a Screen Reader

This content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.

Apple Sucrose Transporter SUT1 and Sorbitol Transporter SOT6 Interact with Cytochrome b5 to Regulate Their Affinity for Substrate Sugars

Ren-Chun Fan, Chang-Cao Peng, Yan-Hong Xu, Xiao-Fang Wang, Yan Li, Yi Shang, Shu-Yuan Du, Rui Zhao, Xiao-Yan Zhang, Ling-Yun Zhang and Da-Peng Zhang
Plant Physiology
Vol. 150, No. 4 (Aug., 2009), pp. 1880-1901
Stable URL: http://www.jstor.org/stable/40537903
Page Count: 22
  • Read Online (Free)
  • Subscribe ($19.50)
  • Cite this Item
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Apple Sucrose Transporter SUT1 and Sorbitol Transporter SOT6 Interact with Cytochrome b5 to Regulate Their Affinity for Substrate Sugars
Preview not available

Abstract

Sugar transporters are central machineries to mediate cross-membrane transport of sugars into the cells, and sugar availability may serve as a signal to regulate the sugar transporters. However, the mechanisms of sugar transport regulation by signal sugar availability remain unclear in plant and animal cells. Here, we report that a sucrose transporter, MdSUTl, and a sorbitol transporter, MdSOT6, both localized to plasma membrane, were identified from apple (Malus domestica) fruit. Using a combination of the split-ubiquitin yeast two-hybrid, immunocoprecipitation, and bimolecular fluorescence complementation assays, the two distinct sugar transporters were shown to interact physically with an apple endoplasmic reticulum-anchored cytochrome b5 MdCYB5 in vitro and in vivo. In the yeast systems, the two different interaction complexes function to upregulate the affinity of the sugar transporters, allowing cells to adapt to sugar starvation. An Arabidopsis (Arabidopsis thaliana) homolog of MdCYB5, AtCYB5-A, also interacts with the two sugar transporters and functions similarly. The point mutations leucine-73 →proline in MdSUTl and leucine-117 → proline in MdSOT6, disrupting the bimolecular interactions but without significantly affecting the transporter activities, abolish the stimulating effects of the sugar transporter-cytochrome b5 complex on the affinity of the sugar transporters. However, the yeast (Saccharomyces cerevisiae) cytochrome b5 ScCYB5, an additional interacting partner of the two plant sugar transporters, has no function in the regulation of the sugar transporters, indicating that the observed biological functions in the yeast systems are specific to plant cytochrome b5s. These findings suggest a novel mechanism by which the plant cells tailor sugar uptake to the surrounding sugar availability.

Page Thumbnails

  • Thumbnail: Page 
1880
    1880
  • Thumbnail: Page 
1881
    1881
  • Thumbnail: Page 
1882
    1882
  • Thumbnail: Page 
1883
    1883
  • Thumbnail: Page 
1884
    1884
  • Thumbnail: Page 
1885
    1885
  • Thumbnail: Page 
1886
    1886
  • Thumbnail: Page 
1887
    1887
  • Thumbnail: Page 
1888
    1888
  • Thumbnail: Page 
1889
    1889
  • Thumbnail: Page 
1890
    1890
  • Thumbnail: Page 
1891
    1891
  • Thumbnail: Page 
1892
    1892
  • Thumbnail: Page 
1893
    1893
  • Thumbnail: Page 
1894
    1894
  • Thumbnail: Page 
1895
    1895
  • Thumbnail: Page 
1896
    1896
  • Thumbnail: Page 
1897
    1897
  • Thumbnail: Page 
1898
    1898
  • Thumbnail: Page 
1899
    1899
  • Thumbnail: Page 
1900
    1900
  • Thumbnail: Page 
1901
    1901