Expression of a Cloned Full-Length cDNA Encoding Bovine Luteinizing Hormone Receptor in COS-7 Cells

Abstract

A cloned full-length cDNA encoding bovine luteinizing hormone (LH) receptor was expressed in COS-7 cells and the binding activity of the protein to human chorionic gonadotropin (hCG) was examined. Molecular cloning of the bovine LH receptor cDNA was carried out by reverse transcription-polymerase chain reaction using total RNA extracted from a bovine corpus luteum. Three overlapping partial fragments of the receptor cDNA were amplified, sequenced, and engineered to generate the entire cDNA coding sequence and it was subcloned into a mammalian expression vector. Sequence analysis showed a 2,103-nucleotide open reading frame encoding the bovine LH receptor, predicting a putative 26-amino acid signal peptide, and a 675-amino acid mature receptor protein that is 94, 88, 86 and 85% identical to the porcine, human, rat and mouse homologs, respectively. Scatchard analysis of the intact COS-7 cells transfected with the bovine LH receptor cDNA showed high affinity and low capacity of [¹²⁵I]-hCG binding sites on the cells. These results suggest that the protein expressed from the cloned bovine LH receptor cDNA is located on the cell surface with its binding activity to LH/hCG.