Immunoglobulin Superfamily, Member 8 (IGSF8)

By Brij-97 detergent lysis of a T cell line and immunoprecipitation with anti-CD81, micropeptide sequencing of the 75-kD protein, MALDI-TOF mass spectrometry, and PSD analysis, followed by database searching, Clark et al. (2001) obtained a cDNA encoding mouse Pgrl ('prostaglandin regulatory-like') and the amino acid sequence of human PGRL (IGSF8). Sequence analysis predicted that the 613-amino acid Ig superfamily protein, 90% identical to the mouse protein, possesses an N-terminal signal sequence, 4 Ig domains, 3 N-linked glycosylation sites, a transmembrane domain, and a short cytoplasmic tail. Genomic database analysis clustered PGRL into a family of proteins including IGSF2 , IGSF3 , and FPRP. Immunoprecipitation and mutation analysis indicated that CD81 interacts with PGRL containing all 4 Ig domains.