(often referred to simply as the letter I
) is a nucleoside
that is very similar to adenosine; the only difference between the two is that in inosine, an -OH group replaces the -NH2
group in adenosine
. It is not a normal nucleoside component of RNA
, but it can show up in tRNA anticodons
It must be noted that the wobble
rules differ between organisms. For instance, in E. Coli
, inosine in anticodons can pair with the bases adenine, cytosine, or uracil. This is not the case in the yeast Saccharomyces cerevisiae
, where the wobble
is more restricted. In this species of yeast, inosine can only be paired with uracil and cytosine.
See also: wobble
Source: Essential Genetics: A Genomics Perspective by Daniel L. Hartl and Elizabeth W. Jones.
http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/ino_0144.shtml is also interesting, for the curious reader.