Theoretical Studies of the Folding Structures of mRNAs and the Biological Functions in Eukaryotes

In this paper, some theoretical prediction methods of folding structures(mainly secondary structures)of RNAs are presented and reviewed briefly.The constructing method of RNA tertiary structure based on the secondary structure has been explored and the molecularmechanics of RNA tertiary structure has been studied. Specific interactions between the nucleotide sequences of splice sites(5'splice site, 3' splice site and branch point of intron)and some small protein molecules are involved in the splicing process of introns of precursor mRNAs in eukaryotic cells.A lot of analyses of the secondary structures of introns, exon-intron-exons and exon-exons nucleotide segments, have shown that most of the splice sites are situated in the loop regions of secondary structures.Such a structural dist ribution characteristic, which can be taken as a kind of structural signals for recognizing the splice sites, is inaccordance with the chemical reaction mechanism of splicing. After comparative study of the folding structures of mRNAs and the encoded proteins, it has been found that there is a positive correlation between them.The correlation reveals three facts:(1)the numbers of secondary structural units of both structures (that is, hairpin structures in mRNA and-helices and-sheet s in protein), are almost the same;(2)the turns of proteins correspond to the loop regions of mRNA secondary st ructures;(3)the spatial arrangements of st ructural elements of bo th structures are in ag reement.Detailed analysis also shows that the characteristics of codon distributions in mRNA secondary structures are correlated with the conformational propensi ties of amino acids to some extent.These results appear to suggest that probably there is a kind of three -dimensional structural genetic relationship between mRNA and the encoded protein, besides one-dimensional linear genetic relationship.