Pattern analysis of 5S rRNA.

Abstract
Some 200 different 5S rRNA sequences from eubacteria, chloroplasts, mitochondria, archaebacteria and eukaryotes were analyzed for evolutionary kinship relationships and associated sequential features. Group-specific occupation schemes for the 149 positions of an overall alignment were established. Eubacterial, archaebacterial and intermediate occupation schemes all yield a strongly biased base triplet pattern in 1 of the 3 possible reading frames strongest for eubacterial, chloroplastic and archaebacterial, but sill detectable for mitochondrial and eukaryotic cytoplasmic sequences. The frequency of triplets decays in the order RNY > RNR > YNY > YNR; R being a purine (guanine or adenine), Y is a pyrimidine (cytosine or uracil) and N is any base. A strong preference for guanine or cytosine was found in all triplet positions. The effects show no exceptions and are clearly above the level of statistical fluctuations.