Protein Disulfide Oxidoreductases and Other Proteins with a Thioredoxin fold; The thioredoxin (TRX)-like superfamily is a large, diverse group of proteins containing a TRX fold. Many members contain a classic TRX domain with a redox active CXXC motif. They function as protein disulfide oxidoreductases (PDOs), altering the redox state of target proteins via the reversible oxidation of their active site dithiol. The PDO members of this superfamily include the families of TRX, protein disulfide isomerase (PDI), tlpA, glutaredoxin, NrdH redoxin, and bacterial Dsb proteins (DsbA, DsbC, DsbG, DsbE, DsbDgamma). Members of the superfamily that do not function as PDOs but contain a TRX-fold domain include phosducins, peroxiredoxins, glutathione (GSH) peroxidases, SCO proteins, GSH transferases (GST, N-terminal domain), arsenic reductases, TRX-like ferredoxins and calsequestrin, among others.

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gi 15240039  91 ALASQKeATVLEFYSHKCRLCNSLLKFVLEVEKRNSNWLSITMADAENEKWFPELLHYDVKYVPCFVLLDKNGQALA 167
Cdd:cd02950  16 ALSNGK-PTLVEFYADWCTVCQEMAPDVAKLKQKYGDQVNFVMLNVDNPKWLPEIDRYRVDGIPHFVFLDREGNEEG 91

TRX-like protein A (TxlA) family; TxlA was originally isolated from the cyanobacterium Synechococcus. It is found only in oxygenic photosynthetic organisms. TRX is a small enzyme that participate in redox reactions, via the reversible oxidation of an active site dithiol present in a CXXC motif. Disruption of the txlA gene suggests that the protein is involved in the redox regulation of the structure and function of photosynthetic apparatus. The plant homolog (designated as HCF164) is localized in the chloroplast and is involved in the assembly of the cytochrome b6f complex, which takes a central position in photosynthetic electron transport.

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gi 15240039  91 ALASQKeATVLEFYSHKCRLCNSLLKFVLEVEKRNSNWLSITMADAENEKWFPELLHYDVKYVPCFVLLDKNGQALA 167
Cdd:cd02950  16 ALSNGK-PTLVEFYADWCTVCQEMAPDVAKLKQKYGDQVNFVMLNVDNPKWLPEIDRYRVDGIPHFVFLDREGNEEG 91

TRX-like protein A (TxlA) family; TxlA was originally isolated from the cyanobacterium Synechococcus. It is found only in oxygenic photosynthetic organisms. TRX is a small enzyme that participate in redox reactions, via the reversible oxidation of an active site dithiol present in a CXXC motif. Disruption of the txlA gene suggests that the protein is involved in the redox regulation of the structure and function of photosynthetic apparatus. The plant homolog (designated as HCF164) is localized in the chloroplast and is involved in the assembly of the cytochrome b6f complex, which takes a central position in photosynthetic electron transport.

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gi 15240039  91 ALASQKeATVLEFYSHKCRLCNSLLKFVLEVEKRNSNWLSITMADAENEKWFPELLHYDVKYVPCFVLLDKNGQALA 167
Cdd:cd02950  16 ALSNGK-PTLVEFYADWCTVCQEMAPDVAKLKQKYGDQVNFVMLNVDNPKWLPEIDRYRVDGIPHFVFLDREGNEEG 91

TRX family; composed of two groups: Group I, which includes proteins that exclusively encode a TRX domain; and Group II, which are composed of fusion proteins of TRX and additional domains. Group I TRX is a small ancient protein that alter the redox state of target proteins via the reversible oxidation of an active site dithiol, present in a CXXC motif, partially exposed at the protein's surface. TRX reduces protein disulfide bonds, resulting in a disulfide bond at its active site. Oxidized TRX is converted to the active form by TRX reductase, using reducing equivalents derived from either NADPH or ferredoxins. By altering their redox state, TRX regulates the functions of at least 30 target proteins, some of which are enzymes and transcription factors. It also plays an important role in the defense against oxidative stress by directly reducing hydrogen peroxide and certain radicals, and by serving as a reductant for peroxiredoxins. At least two major types of functional TRXs have been reported in most organisms; in eukaryotes, they are located in the cytoplasm and the mitochondria. Higher plants contain more types (at least 20 TRX genes have been detected in the genome of Arabidopsis thaliana), two of which (types f amd m) are located in the same compartment, the chloroplast. Also included in the alignment are TRX-like domains which show sequence homology to TRX but do not contain the redox active CXXC motif. Group II proteins, in addition to either a redox active TRX or a TRX-like domain, also contain additional domains, which may or may not possess homology to known proteins.

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gi 15240039  91 ALASQKEATVLEFYSHKCRLCNSLLKFVLEVEKRNSNwLSITMADAENEKWFPEllHYDVKYVPCFVLLdKNGQALAK 168
Cdd:cd02947   5 ELIKSAKPVVVDFWAPWCGPCKAIAPVLEELAEEYPK-VKFVKVDVDENPELAE--EYGVRSIPTFLFF-KNGKEVDR 78