Hematopoietic cell signal transducer - Q9UBK5 (HCST_HUMAN)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

 
Function
Transmembrane adapter protein which associates with KLRK1 to form an activation receptor KLRK1-HCST in lymphoid and myeloid cells; this receptor plays a major role in triggering cytotoxicity against target cells expressing cell surface ligands such as MHC class I chain-related MICA and MICB, and UL16-binding proteins (ULBPs); these ligands are up-regulated by stress conditions and pathological state such as viral infection and tumor transformation. Functions as docking site for PI3-kinase PIK3R1 and GRB2. Interaction of ULBPs with KLRK1-HCST triggers calcium mobilization and activation of the PIK3R1, MAP2K/ERK, and JAK2/STAT5 signaling pathways. Both PIK3R1 and GRB2 are required for full KLRK1-HCST-mediated activation and ultimate killing of target cells. In NK cells, KLRK1-HCST signaling directly induces cytotoxicity and enhances cytokine production initiated via DAP12/TYROBP-associated receptors. In T-cells, it provides primarily costimulation for TCR-induced signals. KLRK1-HCST receptor plays a role in immune surveillance against tumors and is required for cytolysis of tumors cells; indeed, melanoma cells that do not express KLRK1 ligands escape from immune surveillance mediated by NK cells. UniProt
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Subunit Structure
Interacts with CLEC5A (By similarity). Forms an CLEC5A/TYROBP/HCST trimolecular complex depending almost solely on TYROBP (By similarity). Homodimer; Disulfide-linked. Heterohexamer composed of four subunits of HCST/DAP10 and two subunits of KLRK1. Interacts (via transmembrane domain) with KLRK1 (via transmembrane domain); the interaction is required for KLRK1 NK cell surface and induces NK cell-mediated cytotoxicity. Interacts with PIK3R1 and GRB2. UniProt
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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