L17 MCB121

L17 MCB121 - First identified in 1977 as a histone...

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Unformatted text preview: First identified in 1977 as a histone modification in mammals 76 aa, 8.5 kDa small protein found in all eukaryotes, highly conserved sequence Herschko, Ciechanover and Rose *- showed that it was required for in vitro protein degradation in reticulocyte extracts Ubiquitin linked at C- terminus (at top on images) to F-lysyl groups on proteins via isopeptide bond Ubiquitin * Awarded Nobel Prize in Chemistry, 2004 Ubiquitylation can target proteins for degradation • Ubiquitin ligases can add chains of ubiquitin to target proteins (UbK48 connects links in chain) • General system targets improperly folded proteins • Specific ubiquitin ligases (E3 proteins) target specific proteins for regulated degradation Target The Ubiquitylation Pathway S E2 Target S S E1 E3 Target Target E2 E2 E3 S E2 E1 - Ubiquitin Activating (UBA) Enzyme • Catalyzes the activation of ubiquitin that is required for attachment to targets • Activation via ubiquitin adenylylation (hence ATP requirement here) • Catalyzes transfer to E1 cysteinyl group- thioester linkage E1 Ubiquitin ATP AMP + PPi The Ubiquitylation Pathway S Target S S E1 E3 Target Target E2 E2...
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This note was uploaded on 04/06/2011 for the course MCB 121 taught by Professor Gasser during the Winter '09 term at UC Davis.

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L17 MCB121 - First identified in 1977 as a histone...

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