Analysis of Open Reading Frames on Untranslated Regions of Mammal Genes

Nearly 19% of 5'UTRs have AUG in reading frame 1, and nearly 22% and 24% of 5'UTRs have AUG in reading frame 2 and 3 respectively.However,for 3'UTR,71% of them have AUG.Most AUGs appear as small ORFs;Analysis of the length of small ORFs and its corresponding intersictronic sequences appears that 3'UTR is far longer than 5'UTR,but there are almost no difference between the length of small ORFs.However,the average number of small ORF contained in per 3'UTR is obviously more than the average number of small ORF contained in per 5'UTR,and dIC(downstream intersictronic sequences) is longer than uIC(upstream intersictronic sequences);The second type of IC sequences(sequences between open reading frames in UTR) is shorter than another two types of IC sequences(a segment of UTR sequence behind the last open reading frame),and there are relatively more stop codons in the second type of IC sequence;CAI value of uORF is significantly larger than CAI value of dORF.