Abstract: Disclosed are (1) a human luteinizing hormone-human chorionic gonadotropin receptor protein, (2) a DNA comprising a CDNA segment coding for a human luteinizing hormone-human chorionic gonadotropin receptor protein, SEQ ID NO:2 (3) a transformant carrying a DNA comprising a cDNA segment SEQ ID NO:1 coding for a human luteinizing hormone-human chorionic gonadotropin receptor protein, and (4) a method for preparing a human luteinizing hormone-human chorionic gonadotropin receptor protein which comprises cultivating the transformant described in (3), accumulating a protein SEQ ID NO:2 in a culture broth, and collecting the same, whereby the structure and properties of the receptor protein are made clear and the mass production thereof by recombinant technology is pioneered.