CLONING AND EXPRESSION OF THE 58 KD-BETA SUBUNIT OF THE INHIBITORY GLYCINE RECEPTOR

The inhibitory glycine receptor (GIyR) mediates postsynaptic inhibition in spinal cord and other regions of the CNS. Purified mammalian GIyR contains two membrane-spanning subunits of 48 kd (a) and 58 kd (β) plus a 93 kd receptor-associated cytoplasmic protein. Here, the primary structure of the (β) subunit was deduced from cDNAs isolated from rat spinal cord and brain cDNA libraries. The predicted amino acid sequence exhibits 47% identity to the previously characterized rat a, polypeptide. Northern blot analysis revealed high levels of (β) subunit transcripts in postnatal spinal cord, cerebellum, and cortex. Nuclear injection into Xenopus oocytes of a β) subunit cDNA engineered for efficient expression generated weak glycine-activated chloride currents that were insensitive to the classic GIyR antagonist, strychnine. Our data indicate β differential expression of GIyR α and β) subunits in the rat nervous system and support a structural role of the (β) polypeptide in the native receptor complex. © 1990.