HLA-G belongs to the HLA class I heavy chain paralogues. This class I molecule is a heterodimer consisting of a heavy chain and a light chain (beta-2 microglobulin). The heavy chain is anchored in the membrane. HLA-G is expressed on fetal derived placental cells. The heavy chain is approximately 45 kDa and its gene contains 8 exons. Exon one encodes the leader peptide，exons 2 and 3 encode the alpha1 and alpha2 domain，which both bind the peptide，exon 4 encodes the alpha3 domain，exon 5 encodes the transmembrane region，and exon 6 encodes the cytoplasmic tail. [provided by RefSeq，Jul 2008]