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Plants and Prokaryotes Conserved (PCC) domain This is a Plants and Prokaryotes Conserved (PPC) domain found in proteins that contain AT-hook motifs pfam02178 which strongly suggests a DNA-binding function for the proteins as a whole. Proteins with PPC domains are found in Bacteria, Archaea and the plant kingdom.The PPC domain has a single alpha-helix packed against an antiparallel beta-sheet, which is formed by five beta-strands. There are three highly conserved histidine residues, eg at 117, 119 and 133 in Swiss:Q46QL5 which appear to form a zinc-binding site, and the domain has been observed to form homotrimers. The domain co-occurs with a thioredoxin-like domain in uncharacterized cyanobacterial proteins.
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