Cryptochrome 4: Difference between revisions
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==Cryptochrome 4== | ==Cryptochrome 4== | ||
<StructureSection load='6pu0' size='340' side='right' caption=' | <StructureSection load='6pu0' size='340' side='right' caption='Pigeon crypto chrome 4 complex with FAD, triethylene glycol, ethanediol, glycerol and PEG (PDB code [[6pu0]])' scene=''> | ||
== Description == | == Description == | ||
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== Composition & Function == | == Composition & Function == | ||
This protein's gene has 1,584 base pairs corresponding to 527 amino acid residues<ref name="B"/>. It is made of a single chain and comprised mostly of alpha helices. The photosensitizer in this system that contributes to the CIDNP function for this protein is flavin adenine dinucleotide,<scene name='84/841086/Fad_highlight/3'>FAD</scene>. Cryptochrome 4 contains a DNA photolyase homology domain, an FAD binding domain, and four tryptophan residues thought to be involved in radical-pair formation known as the <scene name='84/841086/Trp_tetrad_fad_and_tyr319/1'>Trp-tetrad</scene><ref name="A"/>. | This protein's gene has 1,584 base pairs corresponding to 527 amino acid residues<ref name="B"/>. It is made of a single chain and comprised mostly of alpha helices. The photosensitizer in this system that contributes to the CIDNP function for this protein is flavin adenine dinucleotide, <scene name='84/841086/Fad_highlight/3'>FAD</scene>. Cryptochrome 4 contains a DNA photolyase homology domain, an FAD binding domain, and four tryptophan residues thought to be involved in radical-pair formation known as the <scene name='84/841086/Trp_tetrad_fad_and_tyr319/1'>Trp-tetrad</scene><ref name="A"/>. | ||
The residue <scene name='84/841086/Asn391_highlight/2'>Asn391</scene> is adjacent to the N5 position of the FAD isoalloxazine ring which acts to promote the creation of a stable FADH^rad radicle<ref name="A"/>. This function has been shown in cryptochrome 1 proteins which, normally having a Cys instead of a Asn residue at this point, have previously been mutated to have a Asn and exhibited an increase in quantum yield after this change. It is assumed that this function is present in Cryptochrome 4 and thus Asn 391 will lead to a selection of a stable FADH^rad state<ref name="A"/>. | The residue <scene name='84/841086/Asn391_highlight/2'>Asn391</scene> is adjacent to the N5 position of the FAD isoalloxazine ring which acts to promote the creation of a stable FADH^rad radicle<ref name="A"/>. This function has been shown in cryptochrome 1 proteins which, normally having a Cys instead of a Asn residue at this point, have previously been mutated to have a Asn and exhibited an increase in quantum yield after this change. It is assumed that this function is present in Cryptochrome 4 and thus Asn 391 will lead to a selection of a stable FADH^rad state<ref name="A"/>. | ||