TMIGD2 (CD28H) is a 55 kDa glycosylated transmembrane protein that shares approximately 10% amino acid (aa) sequence identity with CD28, CTLA-4, ICOS, and PD-1. Like other CD28 family members, TMIGD2 is an Ig superfamily member with an extracellular IgV-like domain, a transmembrane region, and a cytoplasmic tail. The cytoplasmic tail contains tyrosine residues which can be phosphorylated and a proline-rich domain which associates with multiple Src homology 3 (SH3)-containing signaling molecules. TMIGD2 has multiple functions depending on the cell type and signaling pathways (1). TMIGD2 could also play an important role in cell-cell interactions, cell migration, and angiogenesis.  CD28H is additionally expressed in the skin and epithelium lining the lung, airway, mammary gland, and gastrointestinal tract (2).

1. Janakiram M, Chinai JM, Zhao A, Sparano JA, Zang X. HHLA2 and TMIGD2: new immunotherapeutic targets of the B7 and CD28 families. Oncoimmunology. 2015;4(8):e1026534. Published 2015 Apr 14. doi:10.1080/2162402X.2015.1026534

1. N. Rahimi, K. Rezazadeh, J. E. Mahoney, E. Hartsough, and R. D. Meyer, “Identification of IGPR-1 as a novel adhesion molecule involved in angiogenesis,” Molecular Biology of the Cell, vol. 23, no. 9, pp. 1646–1656, 2012.