Rna - Complement Of Uracil

Question

[Sefakilic]

As far as I know (and as I read everywhere), in RNA uracil may bind to adenine with two hydrogen bonds. However in the paper "A computer scientist's guide to molecular biology" by Kari et al. [1], at the end of 2nd section, it says

In RNA, C is complementary to G, and U is complementary to A and G. ... except that in RNA U takes place of T as the complement of A, and is also complementary to G.

Is something wrong with this part, or in some cases is it possible?

[1] www.csd.uwo.ca/~lila/pdfs/guidetoMB.pdf

[Neilfws]

This is more a molecular biology than a bioinformatics question However, since you reference a work for computer scientists, I think we'll let it stand.

Answer 1

[Neilfws]

Yes, uracil-guanine pairing can occur. The article is referring to wobble base pairs, also known as non-Watson-Crick base pairs, which can occur at the third codon position.

Read the Wikipedia entry; it's clearer and less clumsy than the sentence you quoted.

[Gustavo]

Indeed not the clearest of sentences. It isn't talking about third codon positions though: it correctly describes the G:U pairing, which is possible essentially anywhere in RNA structure. tRNAs, miRNAs... you name it, they use G:U bonds, without a coding context.

[Neilfws]

OK. So the Wikipedia entry is quite specific to 3rd codon pairing but as Gustavo says, it can occur elsewhere.