Cloning and tissue expression of two putative steroid membrane receptors.

We have cloned two human putative steroid binding membrane proteins, termed Hpr6.6 and Dg6. Hpr6.6 is the human homolog of a previously cloned porcine progesterone binding protein. Both proteins contain a putative transmembrane domain and a highly conserved stretch of 58 amino acids. Hpr6.6 mRNA is expressed predominantly in liver and kidney, whereas Dg6 mRNA is preferentially expressed in placenta. Hpr6.6 is located on the X chromosome and dg6 on chromosome 4. The two proteins are the first putative steroid membrane receptors cloned from man.