Glucagon synthesis with mRNA preparation of a glucagon-producing tumor (IT-1).
Nucleic acids were extracted from the tumor (IT-1) and purified to give poly (A)-containing RNA, which was subjected to protein synthesis in vitro with a wheat germ extract. Gel-filtration (Bio Gel P-30) profiles of the translated product showed the presence of glucagon-like substance, and the results of treatment of fractions with glucagon antibodies (30K or K4023) showed the possibility that translated products contained true-glucagon. This confirms glucagon synthesis in IT-1. The molecular weight of the translated glucagon was estimated to be 3,000 from the K-value. The time courses of the glucagon synthesis were examined in cultured tumor cells (ITC-1) using 3H-leucine as a tracer. A large molecular weight protein was already detected after pulse labeling for 1 h. The amount of labeled glucagon in the cells was shown to be maximum at 1 h. True-glucagon was converted at 3 h to smaller molecular weight peptides which reacted with the C-terminal antibody of glucagon. In vitro protein synthesis, peptides with molecular weights of around 10,000 were major products in 15-30 min.
Sato
J
J
Department of Internal Medicine, Tokyo Medical College, Japan.
D007516:Adenoma, Islet Cell / Q000378:metabolism*; D000818:Animals; D002850:Chromatography, Gel; D006224:Cricetinae; D005934:Glucagon / Q000096:biosynthesis*; D005935:Glucagonoma / Q000378:metabolism*; D066298:In Vitro Techniques; D010190:Pancreatic Neoplasms / Q000378:metabolism*; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000502:physiology*
D012333:RNA, Messenger; D005934:Glucagon