Sandbox TYRP1: Difference between revisions
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The cystein-rich domain and the tyrosinase-like subdomain stongly interact together by the last loop of the cystein-rich domain preceding the N-terminal domain. The role of the cystein-rich domain is still unknown, it is only found in mammalians but 3D-structure highlights two pairs of short antiparallel beta-strands which create loops. This domain is stabilize by five disulfide bounds and is located at the opposite of the active site. It is sad that the cystein_rich domain might help to the formation of a complexe between TYR and TYRP2.<ref name="Xlai"/> | The cystein-rich domain and the tyrosinase-like subdomain stongly interact together by the last loop of the cystein-rich domain preceding the N-terminal domain. The role of the cystein-rich domain is still unknown, it is only found in mammalians but 3D-structure highlights two pairs of short antiparallel beta-strands which create loops. This domain is stabilize by five disulfide bounds and is located at the opposite of the active site. It is sad that the cystein_rich domain might help to the formation of a complexe between TYR and TYRP2.<ref name="Xlai"/> | ||
TYRP1 has six sites of N-glygosylation which are important for maturation of the protein (Asn 96, 104,181,304,350,385). On our 3D structure all these sites are glycosylated. | |||
=== The active site === | === The active site === | ||
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== Comparison between enzymes of Tyrosinase family == | == Comparison between enzymes of Tyrosinase family == | ||
In mammals, three enzymes of Tyrosinase family may be involved in biosynthesis of melanin. [[Tyrosinase]] (TYR) reacts two times in the mechanism whereas Tyrosinase Related Protein 1 and 2 (TYRP1 and TYRP2) probably catalyze only one reaction in this biosynthesis. TYR is an oxydoreductase,TYRP2 seems to act as a tautomerase and the exact role in melanin synthesis of human TYRP1 is still under debate. In fact in mices, TYRP1 can especially catalyze the reaction of DHICA in eumelanin but human TYR can also do the same. It is said that TYRP1 can play a significant role in proliferation of melanosomes.<ref name = "decker"/> | In mammals, three enzymes of Tyrosinase family may be involved in biosynthesis of melanin. [[Tyrosinase]] (TYR) reacts two times in the mechanism whereas Tyrosinase Related Protein 1 and 2 (TYRP1 and TYRP2) probably catalyze only one reaction in this biosynthesis. TYR is an oxydoreductase,TYRP2 seems to act as a tautomerase and the exact role in melanin synthesis of human TYRP1 is still under debate. In fact in mices, TYRP1 can especially catalyze the reaction of DHICA in eumelanin but human TYR can also do the same. It is said that TYRP1 can play a significant role in proliferation of melanosomes.<ref name = "decker"/>. No human cristal structure is available for TYR, so thanks to cristal structure of TYRP1, it is possible to deduce a good model of TYR. | ||
(Image à faire reaction chimique) | (Image à faire reaction chimique) | ||
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After that there is a transmembrane alpha helix followed by a short cytoplasmic sequence on the C-terminal chain. <ref name = "decker"/> | After that there is a transmembrane alpha helix followed by a short cytoplasmic sequence on the C-terminal chain. <ref name = "decker"/> | ||
(image à faire) | (image à faire) | ||
According to crystal knowledges, it is said that TYRP1 and TYR can bind the same substrats. | |||
The three enzymes have several sites of N-glycosylation which are important for their maturation, two of these sites are shared by the three enzymes. TYRP1 and 2 have both six sites and among them, four are exactly the same. <ref name="Xlai"/> | |||
These three proteins share similar active sites. Metal ions interact with three histidines. | These three proteins share similar active sites. Metal ions interact with three histidines. | ||
==== Differences: ==== | ==== Differences: ==== | ||
The main difference between these three | The main difference between these three enzyme is the nature of metal ions they bind on the active site. TYRP1 and TYRP2 bind two zinc ions whereas TYR binds two copper ions. | ||
Contrary to TYRP1 and TYRP2, TYR contains six sites of N-glycsylation. | |||
Interet des ions !!! | Interet des ions !!! | ||
The binds between the protein and its inhibitors are not affected by change in hydrogen bounds. It can be interesting to study this property to design better inhibitors. The future discovery of TRP1 role in melanin synthesis may be a breakthrough for cosmetic industry. <ref name = "decker"/> | The binds between the protein and its inhibitors are not affected by change in hydrogen bounds. It can be interesting to study this property to design better inhibitors. The future discovery of TRP1 role in melanin synthesis may be a breakthrough for cosmetic industry. <ref name = "decker"/> | ||
