User:Alexander Rudecki/Sandbox 1: Difference between revisions
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==Function== | ==Function== | ||
[[Image:Cyclase_reaction.png|thumb|500px|right|Figure 5. | [[Image:Cyclase_reaction.png|thumb|500px|right|Figure 5. DromeQC-mediated cyclization of a terminal glutamine residue forming pyroglutamic acid (pGlu).]] | ||
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. | 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. | ||