GTP-binding protein SAR1b (SAR1B)
The protein contains 198 amino acids for an estimated molecular weight of 22410 Da.
Involved in transport from the endoplasmic reticulum to the Golgi apparatus. Activated by the guanine nucleotide exchange factor PREB. Involved in the selection of the protein cargo and the assembly of the COPII coat complex. (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.
- 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.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
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.
Biological Process
Antigen processing and presentation of exogenous peptide antigen via MHC class II
Antigen processing and presentation of peptide antigen via MHC class I
Cellular protein metabolic process
COPII vesicle coating
Endoplasmic reticulum to Golgi vesicle-mediated transport
Intracellular protein transport
Membrane organization
Positive regulation of protein exit from endoplasmic reticulum
Post-translational protein modification
Protein N-linked glycosylation via asparagine
Regulation of COPII vesicle coating
Small molecule metabolic process
Vesicle organization
The reference OMIM entry for this protein is 246700
Chylomicron retention disease; cmrd
Anderson disease; andd
Lipid transport defect of intestine
Hypobetalipoproteinemia with accumulation of apolipoprotein b-like protein in intestinal cells
A number sign (#) is used with this entry because chylomicron retention disease (CMRD), also referred to as Anderson disease, is caused by homozygous or compound heterozygous mutation in the SAR1B gene (607690) on chromosome 5q31.
DESCRIPTION
Chylomicron retention disease is an autosomal recessive disorder of severe fat malabsorption associated with failure to thrive in infancy (Dannoura et al., 1999).CLINICAL FEATURES
Anderson et al. (1961), Lamy et al. (1967) and Silverberg et al. (1968) described infants with severe steatorrhea. An intestinal defect in lipid transport and a failure of chylomicron formation was suggested, similar to that observed in abetalipoproteinemia (200100). However, neither acanthocytosis nor neuroocular symptoms occurred in Anderson disease. Bouma et al. (1986) described 7 cases (3 young adults and 4 children) in 5 kindreds with Anderson disease. Several of the patients were of Algerian descent. All presented with severe diarrhea in childhood and had a varying degree of growth retardation. The diagnosis was established by the finding of fat-laden enterocytes in small bowel biopsies. The transmission pattern was consistent with autosomal recessive inheritance. Enterocytes isolated from intestinal biopsies of patients after an overnight fast show numerous fat droplets, as in abetalipoproteinemia. Immunoenzymatic staining of enterocytes showed large amounts of material that reacted with a polyclonal antiserum to apolipoprotein B (107730) and a monoclonal antibody to B48. Roy et al. (1987) and Kane and Havel (1989) described chylomicron retention disease. Roy et al. (1987) reported 8 affected infants and distinguished the disorder from abetalipoproteinemia. One of the patients had mild acanthocytosis and 3 patients in their teens had mild peripheral neuropathy with diminished or absent deep tendon reflexes and diminished vibratory sense, and definite or borderline mental retardation. All showed severe growth retardation, steatorrhea, and malnutrition with hypoalbuminemia in 3 and undetectably low plasma vitamin E levels in 5. Although none had retinitis pigmentosa, some showed mild defects in color vision. Nemeth et al. (1995) described 2 sibs with fat malabsorption and jejunal chylomicron retention. Plasma lipoproteins were studied in the patients and their first-degree Relatives. The patients were a 14-year-old girl and her 8-year-old brother. Compared to healthy controls, they both had low fasting plasma concentrations of plasma total, HDL, and LDL cholesterol, as well as of apolipoproteins A-I (107680) and B. No increase in plasma lipoprotein levels or detectable apo B-48 was observed following an oral fat load. Histologic studies of jejunal biopsy specimens obtained during fasting and 1 hour postprandially showed severe steatosis, and an apparent block of chylomicron secretion from the endoplasmic reticulum into the Golgi apparatus was observed by electron microscopy. Liver biopsy specimens showed moderate steatosis and ultrastructural changes similar to those in the enterocytes. One healthy sister had a normal plasma lipoprotein pattern, and showed increased plasma triglyceride levels as well as the presence of apo B-48 following an oral fat load. Both parents had normal plasma total cholesterol levels, but clearly reduced fasting concentrations of HDL cholesterol and apo A-I. Nemeth et al. (1995) suggested that at least in this family, determination of plasma apo A-I levels might thus ... More on the omim web site
Feb. 2, 2018: Protein entry updated
Automatic update: Uniprot description updated
Dec. 19, 2017: Protein entry updated
Automatic update: Uniprot description updated
Nov. 23, 2017: Protein entry updated
Automatic update: Uniprot description updated
June 20, 2017: Protein entry updated
Automatic update: comparative model was added.
March 25, 2017: Additional information
No protein expression data in P. Mayeux work for SAR1B
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 246700 was added.