Mouse secreted B7-1, also known as CD80, GenBank Accession No. NM_009855, a.a 38-246, fused at the C-terminus of the Fc portion of human IgG1, with C-terminal Avi-tag, expressed in a HEK293 cell expression system and enzymatically biotinylated using Avi-tag™ technology. MW=52 kDa. Biotinylation is confirmed to be ≥90%.