Molecular cloning and restriction mapping of human lymphotoxin gene

In order to clone the human lymphotoxin (HuLT) gene, we practiced a concise and time-saving method: homologous recombination in vivo (1). By using the mouse lymphotoxin (MuLT) cDNA (1.3 kb) as a probe, we isolated the HuLT gene from a human genomic library which was constructed with cosmid pcos2EMBL as a vector. After linearization, the recombinant cosmid was partially digested with BamHI, EcoRI, PstI, and PvuII respectively, and either cos end was labelled by hybridization with radioactive oligos complementary to the cohesive end sequence (2). The physical map of HuLT gene was made by this method.