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ARS Home » Research » Publications at this Location » Publication #71648
Title: CLONING THE PROTON-SUCROSE SYMPORTER FROM SUGAR BEET

Author
item LU, MEI-YEH - PLANT BIOLOGY UOFI URBANA
item BUSH, DANIEL

Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Sucrose transporters are important components of the assimilate partitioning pathway in many plants. In sugar beet, a key sucrose carrier in assimilate partitioning is the proton-sucrose symporter that mediates phloem loading. Our lab has described the transport properties of this carrier using purified plasma membranes and imposed proton electrochemcial potential differences. More recently, we have cloned this porter using RT-PCR and sequence information derived from conserved regions of previously cloned symporters. Two PCR fragments showed good sequence identity to the previously cloned sucrose symporters. A full-length clone was isolated for one of these from a sugar beet cDNA library. The clone contains 1939 nt that includes an ORF that encodes a protein consisting of 539 amino acids. This carrier is 84 percent identical to the spinach clone at the protein level. Northern analyses showed that the gene is primarily expressed in leaves, petioles, and hypocotyls, although low levels of message were detectable in roots. The expression pattern also appeared to be developmentally regulated in leaves. The porter is currently the focus of a detailed molecular analysis of its structure and function using site-directed and random mutagenesis. In addition, transgenic plants are being used to explore the physiological contributions of this carrier in more detail.