In this study, we have isolated a bovine homologue bgl-1 of lethal giant larvae (lgl) tumor suppressor oncogene from bovine brain by RT-PCR using primers designed based on the conserved sequences for lgl family members. The sequence analysis showed that the bgl-1 encodes a 1,036 amino acid polypeptide with the molecular weight of approximately 112 kDa containing a domain characteristic of WD-40 proteins. The amino acid sequence of bgl-1 showed a homology of 98.3 and 87.3% identity to that of mouse and human, respectively. Northern blot analysis showed that bgl-1 was highly expressed in brain, ovary and testis, with moderate expression in liver, uterus, lung and kidney. This suggests that the bgl-1 may play essential roles in each of these organs. The complementation analysis revealed that the bovine bgl-1 partially restored the Na+ tolerance in the absence of yeast lgl homologue, suggesting that bgl-1 is a bovine homologue of the lgl family.