Isolation from a multigene family of the active human gene of the metastasis-associated multifunctional protein 37LRP/p40 at chromosome 3p21.3.

The 37 kD precursor of the 67 kD laminin receptor (37LRP) is a polypeptide whose expression is consistently upregulated in aggressive carcinoma. Interestingly, the 37LRP appears to be a multifunctional protein involved in the translational machinery and has also been identified as p40 ribosome-associated protein. Although highly conserved cDNAs corresponding to this polypeptide have been isolated from several species including vertebrates, invertebrates, plants and prokaryotes, characterization of any of the corresponding active genes has never been reported. In this study, we have cloned an intron-containing fragment which permitted us to isolate the active 37LRP/p40 human gene. This gene contains seven exons and six introns. Ribonuclease protection experiments suggest multiple transcription start sites. The promoter area does not bear a TATA box but contains four Sp1 sites. The first intron is also GC rich containing five Sp1 sites. Intron 4 contains the full sequence of the small nuclear RNA E2 and two Alu sequences are found in intron 3. Fluorescent in situ hybridization localized the 37LRP/p40 active gene on chromosome 3 in the locus 3p21.3 which, interestingly, is a hot spot for genetic alterations in several cancers and particularly in small cell lung carcinoma.