A NOVEL CLASS OF GABA(A) RECEPTOR SUBUNIT IN TISSUES OF THE REPRODUCTIVE-SYSTEM

A novel subunit of the gamma-aminobutyrate, type A (GABA,) receptor fa mily has been identified in human and rat tissues. The subunit display s 30-40% amino acid identity with known family members and represents a distinct subunit class (termed pi). Transcripts of the pi subunit we re detected in several human tissues and were particularly abundant in the uterus, The pi subunit protein call assemble with known GABA(A) r eceptor subunits and confer unique ligand binding properties to the re combinant receptors in which it combines. Most notably, the presence o f the rr subunit alters the sensitivity of recombinant receptors to th e endogenous steroid, pregnanolone. identification of the pi subunit i ndicates a new target for pharmacological manipulation of GABA, recept ors that are located outside of the central nervous system.