Simple Sequence Repeats (SSR) or microsatellites are the regions of DNA where one to few bases are tandemly repeated for few to hundreds of times. Recent availability of complete genome sequences has allowed analysis of SSRs at whole genome level. Occurrences of simple sequence repeats in genome sequences gives a snapshot of in vivo accumulated repeats and should reflect basal level of SSR dynamics in a genome.

This resource documents mono-, di-, tri- and tetra-nucleotide repeats occurring in complete genome / chromosome sequences availble from human, Drosophila, C. elegans, Arabidopsis and yeast

Simple Sequence Repeats are generated due to slippage mediated errorrs during DNA replication, repair and recombination. However, when they occur in coding region, their survival depends on their impact on structure and function of encoded protein. Since repeat tracks are prone to DNA-slippage mediated expansions / deletions, their occurrences in coding regions are limited by non-perturbation of reading frame and tolerance of expanding amino acid stretches in the encoded proteins. Among all possible SSRs, tri-nucleotide repeats or multiples thereof are more common in coding regions

This resource documents, occurrences of codon (tri-nucleotide) repeats in complete Coding DNA Sequence sets of all predicted peptides/ORFs of...
           Drosophila melanogaster (Fruit fly)
           Caenorhabditis elegans (Nematode)
           Saccharomyces cerevisiae (Yeast)