Open Reading Frames Analysis On Untranslated Regions Of Mammal Genes

The open reading frame in untranslated region (UTR) of eukaryotic mRNA plays an important role in the level of gene translation. In this paper, the statistical method was used to study the sequence characteristics of upstream open reading frames (uORFs) in mammal 12991 5'UTR sequences and downstream open reading frames (dORFs) in mammal 15319 3'UTR sequences, and explore the differences between some sequence features of uORF and dORF sequences.Nearly 19%of 5'UTRs had AUG in reading frame 1, nearly 22% and 24% of 5'UTR had AUG in reading frame 2 and 3 respectively. In reading frame 1, 86% of AUGs appear as uORF, in reading frame 2 and 3 are 71% and 70 respectively. However, for 3'UTR, 71% of them had AUG and 85% of these AUGs appear as dORF; The analysis about the sequence length of uORFs , dORFs and corresponding uIC sequences (upstream intersictronic sequences) and dIC sequences (downstream intersictronic sequences) appears that although 3'UTR far longer than 5'UTR , but there are almost no difference between the length of dORF and uORF. However, the average number of dORF which contained in per 3'UTR obviously more than the average number of uORF which contained in per 5'UTR, and dIC is longer than uIC; There are no significant correlation between the length of uIC and its corresponding uORF, but there are significant correlation between the length of dIC and its corresponding dORF. If distribute the intercistronic sequence into two groups: longer than or shorter than its corresponding uORF(dORF), there are all significant correlation between the length of uIC and its corresponding uORF or dIC and its corresponding dORF ; The average size of 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); The single-base content and termination codon content of uIC and dIC are very different from each other; Sequences flanking the initiation codon of uORF and dORF all differed from the kozak context; CAI value of uORF is significantly larger than CAI value of dORF.