User:Alexander Rudecki/Sandbox 1: Difference between revisions

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==Function==

[[Image:Cyclase_reaction.png|thumb|500px|right|Figure 5. DromeQC-mediated cyclization of a terminal glutamine residue forming pyroglutamic acid (pGlu).]]

[[Image:Cyclase_reaction.png|thumb|500px|right|Figure 5. DromeQC-mediated cyclization of a terminal glutamine residue forming pyroglutamic acid (pGlu). The leaving amine group is labelled in red.]]

The N-terminus of many proteins (ie gonadotropin releasing hormone and thyrotropin-releasing hormone) contain a pyroglutamic acid (pGlu) residue<ref>PMID: 196172</ref> (Figure 5, right). A pGlu ‘cap’ protects these proteins against degradation by aminopeptidases, and influences the conformation of the hormone or its associated receptor, leading to their activation<ref name="schilling"/>. Cyclization also leads to decreased basicity in the peptide. Though cyclization of Gln-tRNA to pGlu-tRNA has been shown to occur in papaya latex,<ref>PMID: 4881333</ref> N terminal pGlu formation must be post translational due to an essential methionine that initiates translation in all organisms.

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==Localization==

DromeQC is known to localize in the brain and peripheral nerves of ''D. melanogaster''<ref name="schilling"/>. This fact was unveiled by the discovery of adipokinetic hormone; this protein has an N-terminal pGlu, supporting a post translational modification via DromeQC<ref>PMID: 2117437</ref>. Adipokinetic hormone was found to localize in ~~neurone~~ and nerve endings by immunohistochemistry, suggesting that ~~it functions as~~ a locally released modulator in tissues such as heart and skeletal muscle<ref>PMID: 6342796</ref>. Thus, It has been suggested that DromeQC is part of the secretory pathway, being targeted to secretory vesicles where hormone maturation takes place<ref name="schilling"/>. This claim is supported by a 27 residue signal sequence contained at the N-terminus of DromeQC<ref name="schilling"/>. Further support stems from immunohistochemical evidence that DromeQC and ~~its~~ modified substrate are excreted ~~from the cell, where they can be found in~~ the extracellular medium<ref name="schilling"/>.

DromeQC is known to localize in the brain and peripheral nerves of ''D. melanogaster''<ref name="schilling"/>. This fact was unveiled by the discovery of adipokinetic hormone; this protein has an N-terminal pGlu, supporting a post translational modification via DromeQC<ref>PMID: 2117437</ref>. Adipokinetic hormone was found to localize in neurons and nerve endings by immunohistochemistry, suggesting that this hormone is a locally released modulator in tissues such as heart and skeletal muscle<ref>PMID: 6342796</ref>. Thus, It has been suggested that DromeQC is part of the secretory pathway, being targeted to secretory vesicles where hormone maturation takes place<ref name="schilling"/>. This claim is supported by a 27 residue signal sequence contained at the N-terminus of DromeQC<ref name="schilling"/>. Further support stems from immunohistochemical evidence that DromeQC and modified substrate are excreted into the extracellular medium<ref name="schilling"/>.

==References==

@@ Line 52: / Line 52: @@
 ==Function==
-[[Image:Cyclase_reaction.png|thumb|500px|right|Figure 5. DromeQC-mediated cyclization of a terminal glutamine residue forming pyroglutamic acid (pGlu).]]
+[[Image:Cyclase_reaction.png|thumb|500px|right|Figure 5. DromeQC-mediated cyclization of a terminal glutamine residue forming pyroglutamic acid (pGlu). The leaving amine group is labelled in red.]]
 The N-terminus of many proteins (ie gonadotropin releasing hormone and thyrotropin-releasing hormone) contain a pyroglutamic acid (pGlu) residue<ref>PMID: 196172</ref> (Figure 5, right). A pGlu ‘cap’ protects these proteins against degradation by aminopeptidases, and influences the conformation of the hormone or its associated receptor, leading to their activation<ref name="schilling"/>. Cyclization also leads to decreased basicity in the peptide. Though cyclization of Gln-tRNA to pGlu-tRNA has been shown to occur in papaya latex,<ref>PMID: 4881333</ref> N terminal pGlu formation must be post translational due to an essential methionine that initiates translation in all organisms.
@@ Line 68: / Line 68: @@
 ==Localization==
-DromeQC is known to localize in the brain and peripheral nerves of ''D. melanogaster''<ref name="schilling"/>. This fact was unveiled by the discovery of adipokinetic hormone; this protein has an N-terminal pGlu, supporting a post translational modification via DromeQC<ref>PMID: 2117437</ref>. Adipokinetic hormone was found to localize in neurone and nerve endings by immunohistochemistry, suggesting that it functions as a locally released modulator in tissues such as heart and skeletal muscle<ref>PMID: 6342796</ref>. Thus, It has been suggested that DromeQC is part of the secretory pathway, being targeted to secretory vesicles where hormone maturation takes place<ref name="schilling"/>. This claim is supported by a 27 residue signal sequence contained at the N-terminus of DromeQC<ref name="schilling"/>. Further support stems from immunohistochemical evidence that DromeQC and its modified substrate are excreted from the cell, where they can be found in the extracellular medium<ref name="schilling"/>.
+DromeQC is known to localize in the brain and peripheral nerves of ''D. melanogaster''<ref name="schilling"/>. This fact was unveiled by the discovery of adipokinetic hormone; this protein has an N-terminal pGlu, supporting a post translational modification via DromeQC<ref>PMID: 2117437</ref>. Adipokinetic hormone was found to localize in neurons and nerve endings by immunohistochemistry, suggesting that this hormone is a locally released modulator in tissues such as heart and skeletal muscle<ref>PMID: 6342796</ref>. Thus, It has been suggested that DromeQC is part of the secretory pathway, being targeted to secretory vesicles where hormone maturation takes place<ref name="schilling"/>. This claim is supported by a 27 residue signal sequence contained at the N-terminus of DromeQC<ref name="schilling"/>. Further support stems from immunohistochemical evidence that DromeQC and modified substrate are excreted into the extracellular medium<ref name="schilling"/>.
 ==References==
 <references/>