Binds and retains class I heavy chains in the endoplasmic reticulum during the early period of virus infection, thereby impairing their transport to the cell surface. Also delays the expression of class I alleles that it cannot affect by direct retention. Binds transporters associated with antigen processing (TAP) and acts as a tapasin inhibitor, preventing class I/TAP association. In consequence, infected cells are masked for immune recognition by cytotoxic T-lymphocytes. Human adenovirus C serotype 2 Early E3 18.5 kDa glycoprotein (His & Myc) is expressed in E. coli expression system with N-10xHis and C-Myc tag. The predicted molecular weight is 20.0 kDa and the accession number is P68978.

Bovine coronavirus (strain Mebus) Hemagglutinin-esterase Protein (His) is expressed in yeast with N-6xHis tag. The predicted molecular weight is 47.7 kDa and the accession number is P15776.

Human coronavirus HKU1 (isolate N2) Hemagglutinin-esterase (His) is expressed in E. coli expression system with N-10xHis tag. The predicted molecular weight is 45.9 kDa and the accession number is Q14EB1.