CD99 antigen (CD99)
The protein contains 185 amino acids for an estimated molecular weight of 18848 Da.
Involved in T-cell adhesion processes and in spontaneous rosette formation with erythrocytes. Plays a role in a late step of leukocyte extravasation helping leukocytes to overcome the endothelial basement membrane. Acts at the same site as, but independently of, PECAM1. Involved in T-cell adhesion processes (By similarity). (updated: March 4, 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.
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, is predicted to be membranous by TOPCONS.
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| Variant | Description |
|---|---|
| dbSNP:rs4793 | |
| dbSNP:rs4717 |
Biological Process
Cell adhesion
Homotypic cell-cell adhesion
Positive regulation of neutrophil extravasation
Regulation of immune response
T cell extravasation
Molecular Function
The reference OMIM entry for this protein is 313470
Cd99 antigen, x chromosome; cd99
Mic2 surface antigen, x chromosome; mic2x
Cell surface antigen 12e7, x chromosome
E2 antigen, x chromosome
Cell surface antigen hba-71, x chromosome; hba71
Cell surface antigen o13, x chromosome
Msk5x
DESCRIPTION
CD99 is a 32-kD T-cell surface glycoprotein involved in spontaneous rosette formation with erythrocytes (Bernard et al., 1988). The gene encoding CD99 (MIC2X) is located in the pseudoautosomal region (PAR) at the end of the short arm of the X and Y chromosomes (Goodfellow et al., 1983). See also MIC2Y (450000).CLONING
The monoclonal antibody 12E7 was raised against human leukemia T cells. It detects a 30,000 MW protein which is expressed on all human tissues tested with the possible exception of spermatozoa (Levy et al., 1979). Dracopoli et al. (1985) described a monoclonal antibody, O13, that defines a cell surface antigen that is expressed on most cultured human cells but not on rodent cells. Glycoproteins of 25,000 and 30,000 MW were precipitated by O13. Either the X or the Y chromosome in cultured hybrid cells was sufficient for serologic reactivity with the antiserum. The gene encoding O13 maps to Xp22-pter and apparently escapes lyonization. All of these characteristics suggested that O13 was related or identical to 12E7 and that MSK5X and MSK57 (so-called because the workers were at Sloan-Kettering) were related or identical to MIC2X and MIC2Y. Darling et al. (1986) cloned the MIC2X and MIC2Y genes and concluded that their sequences are closely related or identical. Gelin et al. (1989) isolated a 1.11-kb cDNA from a lambda-gt11 expression library by screening with monoclonal antibodies directed against E2 antigen. The primary structure of E2, deduced from the nucleotide sequence of its gene, comprises 185 amino acids and is devoid of N-linked glycosylation sites. The protein displays an organization typical of an integral membrane protein. Nucleotide sequencing revealed that E2 is the MIC2 gene product.MAPPING
Goodfellow et al. (1983) showed that the gene for the E2 antigen, called MIC2 (M = monoclonal; IC = Imperial Cancer Research Fund; 2 = order of discovery), maps to the band between Xp22.3 and Xpter, where the STS (300747) and Xg (300879) genes are located. Goodfellow et al. (1984) showed that the MIC2X locus, like Xg and STS, escapes lyonization. They identified a homologous locus on the Y chromosome (MIC2Y; 45000) in the euchromatin region Ypter-q11.1. This was the first instance of a clear Y-linked structural gene. Curry et al. (1984) found that the STS, Xg, and MIC2X loci as well as the locus for X-linked chondrodysplasia punctata (302950) were apparently absent in males with deletion of Xp22.32. By in situ hybridization, Buckle et al. (1985) showed that MIC2Y is located on the distal part of Yp, namely, Ypter-p11.2. On the basis of an X/Y translocation in which STS activity was retained with the X chromosome (selected by fusion with an HPRT-deficient mouse cell line) but MIC2X was lost, Geller et al. (1986) concluded that MIC2X is distal to STS. - Pseudogene Mangs and Morris (2007) stated that the sequence identified by Smith and Goodfellow (1994) as MIC2R (CD99L1) is a pseudogene that shares 78% sequence homology with MIC2 (CD99). Smith and Goodfellow (1994) had detected sequences related to exons 1, 4, and 5 of MIC2 on the X and Y chromosomes of humans and other primate species. Isolation of these sequences defined the MIC2R (MIC2-related) locus, which is associated with the second-most proximal CpG-rich island in the human pseudoautosomal region. Genomic sequences from the MIC2R locus showed that it is composed of a single sequence related to exon 1 and at least 4 tandem ... 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
March 16, 2016: Protein entry updated
Automatic update: OMIM entry 313470 was added.
Feb. 24, 2016: Protein entry updated
Automatic update: model status changed
Feb. 24, 2016: Protein entry updated
Automatic update: model status changed
Jan. 24, 2016: Protein entry updated
Automatic update: model status changed