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Title: MOLECULAR ANALYSIS OF AMINO ACID TRANSPORTERS: STRUCTURE, FUNCTION AND MOLECULAR CLONING

Author
item CHEN, LISHAN - UNIV OF ILLINOIS, URB
item LOGIUDICE, JENNI - UNIV OF ILLINOIS, URB
item BUSH, DANIEL

Submitted to: Proceedings of International Plant Membrane Transports
Publication Type: Abstract Only
Publication Acceptance Date: 8/11/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: While plants are photoautotrophic organisms, they contain many heterotrophic tissue systems that must import sugars and amino acids to support growth and development. This resource redistribution process is known as assimilate partitioning and it is a fundamental activity that allows higher plants to function as multicellular organisms. Previous work in our lab identified four amino acid transport systems based on biochemical analysis of transport activity and substrate specificity. Subsequently, we cloned one of these carriers, neutral amino acid transport system II (NAT2), by functional complementation of a yeast transport mutant with a plant cDNA library. Recently, we used in situ hybridization to show that NAT2 is primarily expressed in cotyledons, the root elongation zone, and the root tip. To understand the structure and function of this integral membrane protein, we've used site directed and random mutagenesis of this porter to identify essential amino acid residues and protein domains that contribute to the translocation reaction. For example, we've identified a histidine residue as a critical amino acid residue. In addition, we have identified additional amino acid transporters in Expressed Sequence Tagged cDNAs and by isolating amino acid transport mutants.