Functional properties and molecular structure of central and peripheral neurotensin receptors

Membranes prepared from mammalian brain or intestine contain two types of specific binding sites for neurotensin that differ by their affinity and by their sensitivity to sodium ions, GTP, and the antihistamine drug levocabastine. Only the high affinity sites are present in cell cultures and in soluble extracts of CHAPS-treated membranes. These sites represent functional neurotensin receptors coupled to GTP-binding proteins that regulate intracellular levels of cAMP, cGMP and inositol phosphates in neuroblastoma N1E115 cells. The molecular weight of neurotensin receptors in cells and membrane preparations of various origin is about 110,000.