Identification of seven new human MHC class I region genes around the HLA-F locus.

Using cDNA hybridization selection techniques, we identified seven new genes in a 280 kilobase YAC covering the HLA-F locus. The new genes were mapped back to the YAC by a combination of optical restriction mapping and pulse field gel electrophoresis. Northern analysis of individual clones demonstrated the presence of either different mRNA sizes or different expression patterns. Two of the cDNA clones were expressed only in lymphoid cell lines: one in Jurkat cells (T cell) and another in JY cells (B cell). All the genes lacked sequence similarity to any known classical and non-classical major histocompatibility complex (MHC) class I genes, indicating that the MHC class I region has more functions than anticipated. Of the seven new genes, one is highly similar (97%) to mouse 60S ribosomal protein, and another is homologous to diubiquitin proteins. Of the two G-coupled receptor-like cDNAs, one was fully sequenced and found to be an olfactory receptor-like gene. The study strengthens evidence that the MHC complex not only plays a key role in the immune system, but also contributes to non-immunological functions.