Human CD19, also known as B-lymphocyte antigen CD19, CVID3, and Cluster of Differentiation 19, GenBank Accession No. NM_001770, a.a 21-291, with C-terminal Avi-Tag™ fused to the Fc portion of Human IgG1 and expressed in a HEK293 cell expression system. MW = 59 kDa. This protein runs at a higher apparent M.W. by SDS-PAGE due to glycosylation. This protein is enzymatically biotinylated using Avi-Tag™ technology.