title: Initiation factors in protein synthesis by free and membrane-bound polyribosomes of liver and hepatoma.
abstract: The activity of initiation factors obtained from free and membrane-bound polyribosomes of liver and of transplantable H5123 hepatoma of rats was investigated by using an assay of protein synthesis in vitro in which poly (U)-directed polyphenylalanine synthesis was measured. Initiation factors of membrane-bound polyribosomes prepared by using the anionic detergent deoxycholate exhibited less activity in incorporating [14C]phenylalanyltRNA into polypetides than did initiation factors of free polyribosomes. However, when membrane-bound polyribosomes were prepared after using the non-ionic detergent Triton X-100, no significant differences in activities in polyphenylalanine synthesis were observed between the initiation factors of free and membrane-bound polyribosomes. These results suggest that Triton X-100 is preferable to deoxycholate in the isolation of of initiation factors from polyribosomes. Initiation factors, prepared by using Triton X-100, of free polyribosomes of hepatoma exhibited greater activity in the stimulation of polyphenylalanine synthesis than did the initiation factors of free or membrane-bound polyribosomes of host livers or of membrane-bound polyribosomes of hepatomas.
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D003840:Deoxycholic Acid / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism; D008566:Membranes / Q000378:metabolism; D009374:Neoplasms, Experimental / Q000378:metabolism; D010452:Peptide Biosynthesis; D010448:Peptide Initiation Factors / Q000302:isolation & purification*; D010649:Phenylalanine / Q000378:metabolism; D011072:Poly U; D011092:Polyethylene Glycols / Q000494:pharmacology; D011132:Polyribosomes / Q000187:drug effects / Q000378:metabolism*; D014176:Protein Biosynthesis; D012343:RNA, Transfer; D051381:Rats; D012270:Ribosomes / Q000378:metabolism
chemical_list: D010448:Peptide Initiation Factors; D003840:Deoxycholic Acid; D011072:Poly U; D011092:Polyethylene Glycols; D010649:Phenylalanine; D012343:RNA, Transfer