NKp44
| NKp44 | ||
|---|---|---|
| Properties of human protein | ||
| Mass / length primary structure | 255 amino acids | |
| Secondary to quaternary structure | single-pass type 1 membrane receptor | |
| Isoforms | 3 | |
| Identifier | ||
| Gene name | NCR2 | |
| External IDs | ||
NKp44 (gene: NCR2 ), synonym CD336, is a receptor protein that is located in the plasma membrane of activated NK cells . It belongs to the family of natural cytotoxic receptors (NCR) and has an activating effect on the function of the NK cell after ligand binding.
physiology
NK cells recognize various target structures with this receptor and are thereby activated. As a result, recognized cells are destroyed, the NK cells form cytokines and initiate an adaptive immune response.
Molecular structure
Structurally, the protein consists of an extracellular V-type immunoglobulin- like domain , a transmembrane region with a characteristic lysine and a cytoplasmic domain with a functionally inactive ITIM ( immunoreceptor tyrosine-based activated motif ).
Target structures and target structures expressing cells
The endogenous ligand has not yet been characterized. However, NKp44 recognizes mycobacteria ( M. tuberculosis , M. avium , M. smegmatis , BCG; Nocardia foranicia ) and Pseudomonas aeruginosa , although the recognized structures are not known. NKp44 recognizes the H5 influenza hemagglutinin . The endogenous ligand - NKp44L - is expressed on T cells ; this expression is increased by gp41 of HIV . There is increased NK cell activity in HIV infection; T cells are recognized and eliminated by NK cells via the suspected NKp44 ligand.
Signal transduction
NKp44 binds non-covalently to the ITAM of the signal transduction adapter DAP12 (Karap) via the transmembrane region (lysine ).
Expressing cells
NKp44 is only expressed on activated NK cells, but not on resting NK cells. A subgroup of γδ T cells also express NKp44.
Individual evidence
- ↑ Vitale M. et al .: NKp44, a novel triggering surface molecule specifically expressed by activated natural killer cells, is involved in non-major histocompatibility complex-restricted tumor cell lysis. J Exp Med 187 (12): 2065-72 (1998) PMID 9625766
- ↑ Cantoni C. et al .: NKp44, a triggering receptor involved in tumor cell lysis by activated human natural killer cells, is a novel member of the immunoglobulin superfamily . J Exp Med 189 (5): 787-96 (1999) PMID 10049942
- ↑ Esin S. et al .: Direct binding of human NK cell natural cytotoxicity receptor NKp44 to the surfaces of mycobacteria and other bacteria. In: Infection and Immunity 76 (4): 1719-27 (2008) PMID 18212080
- ↑ Ho JW. et al .: H5-type influenza virus hemagglutinin is functionally recognized by the natural killer-activating receptor NKp44 . J Virol 82 (4): 2028-32 (2008) PMID 18077718
- ↑ Vieillard V. et al .: NK cytotoxicity against CD4 + T cells during HIV-1 infection: a gp41 peptide induces the expression of an NKp44 ligand . Proc Natl Acad Sci USA 102 (31): 10981-6 (2005) PMID 16046540
- ^ Campbell KS. et al .: NKp44 triggers NK cell activation through DAP12 association that is not influenced by a putative cytoplasmic inhibitory sequence. J Immunol 172 (2): 899-906 (2004) PMID 14707061