PREPARATION OF A PHOTOAFFINITY PROBE FOR THE MAN6P IGF-II RECEPTOR

A photoaffinity probe, opentamanniminophenyl)ethyl-(4-azido)salicylami de, was prepared for photolabelling of the mannose 6-phosphate/insulin -like growth factor II receptor. The probe was synthesized from phosph opentamannan and 2-(4-aminophenyl)ethylamine followed by coupling with photosensitive 4-azidosalicylic acid. The I-125-labelled probe was re acted with receptor purified from rat liver under irradiation with ult raviolet light. Fluorography of the reaction product on a polyacrylami de gel effectively detected the receptor coupled to the photoprobe as a molecular mass of 250 kDa. Specific binding of the probe or of radio labelled insulin-like growth factor II was not inhibited by the growth factor or by mannose 6-phosphate, confirming different binding sites to the receptor between the ligands.