Cloning of LL5, a novel protein encoding cDNA from a rat pituitary library

While screening a rat pituitary cDNA library for a peptide hormone receptor, we identified a cDNA that represents a novel gene. The 3.8 kb cDNA has an open reading frame of 2.3 kb encoding a protein of 781 amino acids (M(r) = 87,507). Southern blot analysis of rat, mouse, bovine and human genomic DNAs revealed that a homologous gene is present in these species probably in a single copy. Northern blot analysis showed that in addition to the pituitary gland, the gene is also expressed in other rat tissues. Scanning of DNA and protein databanks revealed no significant homology to any other sequence. Thus, this gene encodes a heretofore unidentified protein.