id author title date pages extension mime words sentences flesch summary cache txt cord-290640-kh2t0kfz O'Connor, Jennifer Black Downstream Ribosomal Entry for Translation of Coronavirus TGEV Gene 3b 2000-03-30 .txt text/plain 5946 283 55 Abstract Gene 3b (ORF 3b) in porcine transmissible gastroenteritis coronavirus (TGEV) encodes a putative nonstructural polypeptide of 27.7 kDa with unknown function that during translation in vitro is capable of becoming a glycosylated integral membrane protein of 31 kDa. In the virulent Miller strain of TGEV, ORF 3b is 5′-terminal on mRNA 3–1 and is presumably translated following 5′ cap-dependent ribosomal entry. Here we report that, whereas mRNA 3 has a sequence predicting leaky scanning for the translation of ORF 3b by the model of Kozak (1989) , experimental results with mutant constructs suggested downstream entry of ribosomes might also be used. To test by in vitro translation whether the 27.7-and 20-kDa gene 3b products (O'Connor and Brian, 1999) are synthesized when ORF 3b is positioned downstream of ORF 3a (beginning at base 337) on synthetic transcripts, uncapped transcripts of pORF3a-3b-4 DNA linearized at the BamHI site 50 nt downstream from the stop codon of gene 4 (Fig. 1C) were translated in either wheat germ extract or rabbit reticulocyte lysate. ./cache/cord-290640-kh2t0kfz.txt ./txt/cord-290640-kh2t0kfz.txt