Ubiquitin-associated domain-containing protein 1 (UBAC1)
The protein contains 405 amino acids for an estimated molecular weight of 45338 Da.
Non-catalytic subunit of the KPC complex that acts as E3 ubiquitin-protein ligase. Required for poly-ubiquitination and proteasome-mediated degradation of CDKN1B during G1 phase of the cell cycle. (updated: April 1, 2015)
Protein identification was indicated in the following studies:
- Goodman and co-workers. (2013) The proteomics and interactomics of human erythrocytes. Exp Biol Med (Maywood) 238(5), 509-518.
- Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
- Hegedűs and co-workers. (2015) Inconsistencies in the red blood cell membrane proteome analysis: generation of a database for research and diagnostic applications. Database (Oxford) 1-8.
- Wilson and co-workers. (2016) Comparison of the Proteome of Adult and Cord Erythroid Cells, and Changes in the Proteome Following Reticulocyte Maturation. Mol Cell Proteomics. 15(6), 1938-1946.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- D'Alessandro and co-workers. (2017) Red blood cell proteomics update: is there more to discover? Blood Transfus. 15(2), 182-187.
- Chu and co-workers. (2018) Quantitative mass spectrometry of human reticulocytes reveal proteome-wide modifications during maturation. Br J Haematol. 180(1), 118-133.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
This protein is annotated as membranous in Gene Ontology.
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| Variant | Description |
|---|---|
| dbSNP:rs11103231 |
Molecular Function
The reference OMIM entry for this protein is 608129
Ubiquitin-associated domain-containing protein 1; ubac1
Uba domain-containing protein 1
Glioblastoma differentiation-related protein 1; gbdr1
Kip1 ubiquitination-promoting complex 2; kpc2
CLONING
By differential display analysis of untreated and EPO (133170)-treated primary human microvascular endothelial cells (HMVECs), followed by HMVEC cDNA library screening, Li et al. (2000) cloned GBDR1. The deduced 404-amino acid protein has a calculated molecular mass of about 44.4 kD. GBDR1 contains a C-terminal helix-loop-helix motif and an SRC (190090) homology-3 (SH3) domain. It has several putative phosphorylation sites, including 8 CK2 (see 115440) sites, as well as 1 N-glycosylation site and 2 N-myristoylation sites. The 5-prime untranslated region of the transcript contains a CpG island, and the 3-prime region contains 2 mRNA instability motifs. Northern blot analysis detected a 1.9-kb transcript expressed in both resting and EPO-stimulated HMVECs and human umbilical vein endothelial cells (HUVECs). Northern blot analysis of a multiple-tissue panel detected ubiquitous GBDR1 expression, with highest levels in heart and skeletal muscle and lowest level in lung. Western blot analysis of HMVEC lysates detected GBDR1 at an apparent molecular mass of about 46 kD. Cell fractionation revealed GBDR1 in the membrane fraction, and detergent treatment indicated that GBDR1 associates with nuclear membranes. In HMVECs, GBDR1 showed a punctate cytoplasmic distribution and a variable number of nuclear speckles. By searching an EST database for sequences similar to rabbit Kpc2, followed by PCR of a human liver cDNA library, Kamura et al. (2004) cloned UBAC1, which they called KPC2. The deduced protein contains an N-terminal ubiquitin-like (UBL) domain and 2 C-terminal ubiquitin-associated (UBA) domains.GENE FUNCTION
Although differential screening indicated that GBDR1 was upregulated following EPO treatment of HMVECs, Li et al. (2000) were unable to confirm upregulation by Northern blot analysis. However, EPO treatment increased the amount of GBDR1 in the nuclear compartment of immunostained HMVECs. In vitro phosphorylation assays determined that GBDR1 is a substrate for CK2, and Li et al. (2000) noted that 2 CK2 phosphorylation sites are near a putative nuclear localization signal. Kamura et al. (2004) found that KPC2 interacted with the proteasome through its UBL domain and with polyubiquitinated proteins through its UBA domains. By immunoprecipitation analysis, they showed that epitope-tagged KPC2 interacted directly with KPC1 (RNF123; 614472) and that the complex exhibited pronounced E3 ubiquitin ligase activity toward p27(KIP1) (CDKN1B; 600778), but not other substrates, in the presence of E1 (UBA1; 314370), and E2 (UBCH5A, or UBE2D1; 602961) enzymes. Both mono- and polyubiquitinated forms of p27(KIP1) were detected, and polyubiquitination required either UBC4 (UBE2D2; 602962) or UBCH5A. The E3 activity of KPC1 toward p27(KIP1) was greater in the absence of PKC2. Overexpression and knockdown studies with mouse fibroblasts revealed that the KPC complex functioned in the cytoplasm, ubiquitinated p27(KIP1) during G1 phase of the cell cycle, and required nuclear export of p27(KIP1) by Crm1 (XPO1; 602559).MAPPING
By somatic cell hybrid analysis and Southern blot analysis, Li et al. (2000) mapped the single-copy UBAC1 gene to chromosome 9. Hartz (2011) mapped the UBAC1 gene to chromosome 9q34.3 based on an alignment of the UBAC1 sequence (GenBank GENBANK AF068195) with the genomic sequence (GRCh37). ... More on the omim web site
May 13, 2019: Protein entry updated
Automatic update: model status changed
Nov. 17, 2018: Protein entry updated
Automatic update: model status changed
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Oct. 27, 2017: Protein entry updated
Automatic update: model status changed
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 608129 was added.
Feb. 24, 2016: Protein entry updated
Automatic update: model status changed