CLONING AND FUNCTIONAL EXPRESSION OF THE HUMAN TYPE-1 SIGMA-RECEPTOR (HSIGMAR1)

We have isolated a cDNA clone from a human placental choriocarcinoma c ell (JAR) cDNA library which codes for a functional type 1 sigma recep tor. An RT-PCR product obtained from guinea pig kidney mRNA using prim ers specific for the guinea pig sigma receptor cDNA was used to screen the cDNA library. The hSigmaR1 cDNA predicts a protein of 223 amino a cids with a single putative transmembrane domain. The amino acid seque nce exhibits 93% identity with the guinea pig sigma receptor. When fun ctionally expressed in HeLa cells, the hSigmaR1 cDNA enhances the bind ing of [H-3]-haloperidol, a sigma receptor ligand, to the HeLa cell me mbranes. The inhibitor specificity of the cloned hSigmaR1 indicates th at it is the type 1 sigma receptor. Several human tissues, including p lacenta, liver, and brain, and several human cell lines express the Si gmaR1 mRNA (1.7 kb) to a variable extent. (C) 1996 Academic Press, Inc .