Ligand for the NKG2D receptor, together with at least ULBP1 and ULBP2. ULBPs activate multiple signaling pathways in primary NK cells, resulting in the production of cytokines and chemokines. Binding of ULBPs ligands to NKG2D induces calcium mobilization and activation of the JAK2, STAT5, ERK and PI3K kinase/Akt signal transduction pathway. Has lower affinity for NKG2D compared to ULBP1 and ULBP2 and induces weaker signaling responses than does ULBP2 or ULBP1. Belongs to the MHC class I family. Note: This description may include information from UniProtKB.