CHARACTERIZATION OF THE SUBSTANCE-P (NK-1) RECEPTOR IN TUNICAMYCIN-TREATED TRANSFECTED CELLS USING A PHOTOAFFINITY ANALOG OF SUBSTANCE-P

Chinese hamster ovary cells expressing the N-glycosylated substance P (NK-1) receptor were treated with the glycosylation inhibitor tunicamy cin and photolabeled with lton-Hunter-p-benzoyl-L-phenylalanine(8)-sub stance P. Two radioactive proteins of M(r) 80,000 and 46,000, represen ting the glycosylated and nonglycosylated substance P (NK-1) receptor, respectively, were observed. The IC50 for the inhibition of photolabe ling of both receptor forms was 0.3 +/- 0.1 nM for substance P and 30 +/- 5 nM for neurokinin A (substance K). Thus, glycosylation of the su bstance P (NK-1) receptor has no detectable effect on the affinity of the substance P (NK-1) receptor for substance P or neurokinin A (subst ance K).