|Mass / length primary structure||428 = 2 x 214 or 403 = 214 + 189 amino acids|
|Secondary to quaternary structure||α + α or α + β|
|Isoforms||α: 2, β: 6|
|Gene name (s)||CD8A , CD8B|
The CD8 or CD8 is a surface protein that has a significant role in the immune system of vertebrates plays.
CD8 is a protein that is embedded in the cell membrane of cytotoxic T cells and is characteristic of this cell type and its direct precursor . CD stands for Cluster of Differentiation . In addition, CD8 is also found on NK cells , thymocytes and dendritic cells . Furthermore, CD8 is also formed in lymphoblastic T-cell lymphoma , in hypopigmented mycosis fungoides and in epitheliotropic T-cell lymphoma in dogs . CD8 is a coreceptor of the T cell receptor . The T-cell receptor recognizes the epitope presented on MHC-I and CD8 binds the MHC-I complex on antigen-presenting cells . All cells in the body that contain nucleus (i.e. no erythrocytes ) produce MHC-I complexes and present short peptides of eight to eleven amino acids on them , which were produced from cellular proteins by proteolysis in the proteasome and introduced into the endoplasmic reticulum via the antigen peptide transporter and there bound by MHC-I complexes. Cytotoxic T cells with CD8 now recognize whether they are viral peptides or peptides of mutated (and thus often cancer-related) proteins. If they recognize foreign peptides and a costimulator is expressed in the presenting target cell , the cytotoxic (CD8) T cell is activated and then the MHC-I-carrying target cell is destroyed.
CD8 exists in different isoforms . Most often an α- homodimer or an α-β- heterodimer (both monomers about 34 kDa ) is formed. CD8 is predominantly a β-sheet with 46% of the amino acids and 2% α-helices , the rest are β-loops . The extracellular part of CD8 binds to α3 of the MHC-I molecule.
- ↑ Klaus D. Elgert: Immunology. John Wiley & Sons, 2009, ISBN 978-0-470-08157-0 , p. 30.
- ↑ Kenneth M. Murphy, Paul Travers, Mark Walport: Janeway - Immunology . Corrected reprint 2014. 7th edition. Springer Spectrum, Berlin 2014, ISBN 978-3-662-44227-2 .
- ↑ Leong, Anthony SY; Cooper, Kumarason; Leong, F Joel WM: Manual of Diagnostic Cytology , 2nd Edition, Greenwich Medical Media, Ltd., 2003, ISBN 1-84110-100-1 , p. 73.
- ↑ J. Fontaine, C. Bovens, p Bettenay, RS Mueller: Canine cutaneous epitheliotropic T-cell lymphoma: a review. In: Veterinary and comparative oncology. Volume 7, Number 1, March 2009, pp. 1-14, doi : 10.1111 / j.1476-5829.2008.00176.x , PMID 19222826 (review).
- ↑ Abul K. Abbas: Cellular and Molecular Immunology. Elsevier Health Sciences, 2014, ISBN 978-0-323-28645-9 , p. 147.
- ↑ William E. Paul: Fundamental Immunology. Lippincott Williams & Wilkins, 2012, ISBN 978-1-451-18203-3 , p. 11.
- ^ DJ Leahy, R. Axel, WA Hendrickson: Crystal structure of a soluble form of the human T cell coreceptor CD8 at 2.6 A resolution. In: Cell. Volume 68, Number 6, March 1992, pp. 1145-1162, PMID 1547508 .