Cloning and expression of an immunoglobulin superfamily gene (IGSF1) in Xq25.

We have isolated a novel full-length cDNA for a gene (IGSF1) located in distal Xq25. This transcript is highly expressed in adult testis and fetal liver but is undetectable in adult liver. A smaller alternate form is highly expressed in adult heart. The gene encodes a protein of 1327 amino acids with several recognizable functional domains. The protein has a putative signal peptide and transmembrane region, 15 potential sites for N-linked glycosylation, and 12 C2-type immunoglobulin (Ig)-like domains. All of the Ig-like domains contain the two conserved cysteine residues that form intradomain disulfide bonds typical of this superfamily. These features are consistent with a possible role for this molecule in cell surface recognition or cell-cell interaction.