Cloning and chromosomal localization of a pseudogene corresponding to a mRNA for a soluble IL-6 receptor

A polymerase chain reaction assay (Lust J.A. et al. (1992). Cytokine 4:96-100) was used to detect a mRNA coding for a soluble IL-6 receptor in human hepatoma cells. In addition to the expected amplification product, we found a sequence (SR4) which could be aligned to it with 78% identity. After cloning and sequencing a genomic 2.5-2.7 kB EcoRI fragment containing SR4, this sequence turned out to be part of a pseudogene corresponding to the transmembrane domain deleted soluble IL-6 receptor. Screening of a panel of interspecies hybrids revealed that it maps to chromosome 9.