Viral unique long protein 16
This family contains members such as UL16 found in the human cytomegalovirus (HCMV). It is an immunoevasin which subverts NKG2D-mediated immune responses by retaining a select group of diverse NKG2D ligands inside the cell. UL16 is a heavily glycosylated 50 kDa type I trans-membrane glycoprotein. The ectodomain folds into a modified version of the a variable (V-type) (immunoglobulin Ig)-like domain. The N-terminal plug region (amino acids 27-50) is covalently linked to the Ig-like core with a disulfide bond. UL16 protein utilizes a three-stranded beta-sheet to engage the alpha-helical surface of the MHC class I-like MICB platform domain. Residues at the center of this beta-sheet mimic a central binding motif employed by the structurally unrelated C-type lectin-like NKG2D to facilitate engagement of diverse NKG2D ligands.
Jiyao W et al.(2023). "The conserved domain database in 2023.",