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Isolation of Physiologically Active Thylakoids and Their Use in Energy-Dependent Protein Transport Assays
Published on: September 28, 2018
Chloroplast TatC plays a direct role in thylakoid (Delta)pH-dependent protein transport
1Horticultural Sciences and Plant Molecular and Cellular Biology, Fifield Hall, University of Florida, Gainesville, FL 32611, USA.
Abstract:
The thylakoid (Delta)pH-dependent pathway transports folded proteins. Identified components include Hcf106 and Tha4. Orthologs of these proteins plus a membrane protein called TatC are essential for the homologous bacterial Tat system. Here we report identification of a chloroplast TatC (cpTatC). cpTatC is an integral thylakoid membrane protein as determined by in vitro chloroplast import and immunoblotting. Antibody to cpTatC specifically inhibited the thylakoid (Delta)pH-dependent pathway in vitro. cpTatC is present in about the same quantity as estimated translocation sites, whereas Hcf106 and Tha4 are present in 5-8-fold excess. These results are relevant to mechanistic models for this system.
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