Human CD28 homolog (CD28H), also known as Transmembrane and immunoglobulin domain-containing protein 2 (TMIGD2) and immunoglobulin and prolinerich receptor 1 (IGPR-1). GenBank Accession No. NM_144615, a.a. 23-150 with C-terminal His-Tag expressed in a HEK293 expression system. MW = 15 kDa.