Distribution of 4.5S1. RNA among rodents and conservation of its nucleotide sequence

It has been shown that small nuclear 4.5S1 RNA and its homologous DNA seque nces occur only in three rodent families: Muridae, Cricetidae, and Spalacid ae. This RNA is suggested to arise about the same evolutionary time as shor t retroposon B2 relative to it. The nucleotide sequences of golden hamster and common mole rat 4.5S1 RNA are highly conservative, as compared with the rat one, which can point out its functional role despite the narrow specie s range of its distribution.