Aptamers - binding and regulation abilities of RNA molecules

Aptamers are single stranded ribo- or deoxyribonucleotides usually 20 to 80 nucleotides in length that occupy a complex three-dimensional structures by intramolecular interactions and bind to small target molecules with high affinity and specificity. Aptamers are generated in vitro using revolutionary technology SELEX (systematic evolution of ligand by exponential enrichment) and its modifications. They have recently attracted considerable attention of the scientific and medical community because of the fact that is possible to prepare aptamers binding practically any target molecule and this is making aptamers promising as diagnostic and therapeutic tools. Aptamers also exist naturally; aptamer domains have been found repeatedly as part of the regulatory elements of gene expression in bacteria, where they act as specific receptors for cellular metabolites. Domain TPP has been also found in plants, fungi and green algae