Assignment of tear lipocalin gene to human chromosome 9q34-9qter

We assigned the gene for tear lipocalin to the long arm of human chromosome 9. Polyadenylated RNA was extracted from lacrimal gland. The coding region for tear lipocalin was amplified, sequenced and used to probe a panel of somatic cell hybrid DNA by Southern blot analysis. Regional mapping was accomplished by probing a panel of subfragments of the indicated chromosome. Restriction of genomic DNA with EcoRI failed to reveal any bands corresponding to the human tear lipocalin gene in mouse-human hybrids all of which lack chromosome 9. Southern blot analysis of human-hamster hybrids demonstrated a human 5.6 kb TaqI restriction fragment that segregated to the q34-qter region of chromosome 9 and assigned the gene for tear lipocalin to this region. Structurally homologous proteins of the lipocalin family, human placental protein 14, human alpha 1 microglobulin, and human brain prostaglandin synthase, have been mapped to this region. We suggest that the gene for tear lipocalin is part of an important lipocalin superfamily gene cluster on chromosome 9 within band q34.