CHARACTERIZATION OF HUMAN 5-HT1 RECEPTORS EXPRESSED IN SF9 INSECT CELLS

Four human 5-HT receptor subtypes (5-HT1A, 5-HT1D alpha, 5-HT1D beta a nd 5-HT1E) have been expressed in Sf9 insect cells. All four human 5-h ydroxytryptamine receptors produced by Sf9 cells had the expected phar macological properties. Surprisingly, levels of expression of these re ceptors were relatively low (1-5 pmol/mg protein). High affinity agoni st binding to the four 5-hydroxytryptamine receptors was reduced to di fferent extents by guanine nucleotides and/or NaCl. This suggests that the nature of receptor-G protein coupling and/or the predominant conf ormational state of the receptors in Sf9 cell membranes varies among t he different receptors. Activation of all four receptors inhibited for skolin-stimulated cAMP formation in intact Sf9 cells. Expression of 5- hydroxytryptamine receptors in Sf9 cells should be useful for purifica tion of these receptors, for studies of post-translational modificatio n and for pharmaceutical screening.