NKG7 is a cDNA clone generated from a human NK-cell clone. The DNA and predicted aa sequence of NKG7 is not homologous with any previously reported genes or peptides. NKG7 mRNA is expressed in activated T cells and in A-LAK cells isolated from the peripheral blood of normal individuals, and in normal human kidney, liver, lung and pancreas. Furthermore, NKG7 mRNA is expressed at high levels in TCR gamma delta-expressing CTL clones, and in some TCR alpha beta-expressing CTL clones (both CD4+ and CD8+), but is not expressed in other TCR alpha beta-expressing CTL clones and in cell lines representing B cells, monocytes, and myeloid cells. NKG7 mRNA is not expressed in normal human brain, heart, or skeletal muscle. Southern hybridization of NKG7 suggests that NKG7 is a single-copy gene localized to chromosome 19. A hydropathicity profile of the predicted 148 aa polypeptide indicates that NKG7 is a type-I integral membrane protein with a 38-aa extracellular domain and a 61-aa cytoplasmic domain. These results indicate that the NKG7 gene encodes a novel cell surface protein expressed in several cell types, including NK cells and T cells.