UbiProt Database - proteins_show

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Protein information

Protein name Breast cancer type 1 susceptibility protein 
Synonyms RING finger protein 53
Gene name BRCA1 , RNF53 .
Source Homo sapiens (Human)
Expression system 293T cells [in 1], Sf9 cells [in 2]
Full length  1863
Precursor  no
Mature form length  1863
Molecular weight (Da)  207721
Swiss-Prot Sequence Version  February 1, 1995 (Sequence version 2)
Comments  Mass spectrometry analysis identified the Lys-6-linked branched ubiquitin fragment from the polyubiquitin chain produced by BRCA1-BARD1 using wild type ubiquitin [1]. Autoubiquitylation [2].


PDB 1JM7 , 1JNX , 1N5O , 1OQA , 1T15 , 1T29 , 1T2U , 1T2V , 1Y98 .

Ubiquitylation features

Ubiquitylation site  

Ubiquitylation type Lys6-linked multi-ubiquitin chain
Features BRCA1-BARD1 preferentially utilizes ubiquitin with a single Lys residue at Lys-6 or Lys-29 to mediate autoubiquitination of BRCA1 in vivo [1]. High molecular weight BRCA1 protein species appeared after treatment with proteasome inhibitors, such as MG-132 and ALLnL [3].

Ubiquitylation/deubiquitylation machinery

E2 Recombinant His6-UbcH5c for the in vitro Ub ligation assay [1]. UbcH5c [2].
E4/AP Not determined
DUB Not determined
Comments The BRCA1-BARD1-mediated Lys-6-linked polyubiquitin chains are deubiquitinated by 26 S proteasome in vitro [1]. In vitro [2].


[1]Nishikawa H, Ooka S, Sato K, Arima K, Okamoto J, Klevit RE, Fukuda M, Ohta T:
Mass spectrometric and mutational analyses reveal Lys-6-linked polyubiquitin chains catalyzed by BRCA1-BARD1 ubiquitin ligase. J Biol.Chem. 2004, 279:3916-3924.
[2]Wu-Baer F, Lagrazon K, Yuan W, Baer R:
The BRCA1/BARD1 heterodimer assembles polyubiquitin chains through an unconventional linkage involving lysine residue K6 of ubiquitin. J Biol.Chem. 2003, 278:34743-34746.
[3]Choi YH:
Proteasome-mediated degradation of BRCA1 protein in MCF-7 human breast cancer cells. Int.J Oncol. 2001, 19:687-693.


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