physical interaction evidence systematic evolution of ligands by exponential amplification evidence A type of evidence arising from a physical interaction analysis where a combinatorial chemistry technique is used to identify oligonucleotides that bind to a target ligand. 2011-01-10T04:23:50Z in vitro evolution evidence SELEX begins with the synthesis of a large oligonucleotide library, either single-stranded DNA or RNA, which consists of random fixed-length sequences flanked by constant 5' and 3' ends that serve as primers. The library is exposed to a target ligand, typically a protein or small organic compound. Unbound sequences are removed, typically with affinity chromatography. Bound sequences are eluted and the nucleic acid is extracted, followed by PCR amplification (RNA is first reverse transcribed). PCR product is converted to single stranded (DNA) or transcribed (RNA). Oligonucleotides are bound to the ligand again and the process is repeated with increasing elution stringency. After several rounds of the process, recovered oligonucleotides are sequenced and analyzed to reveal the binding specificity of the protein. SELEX evidence ECO:0000293 A total of 160 SELEX fragments were cloned and sequenced, which were classified into 29 CRP-binding sequences, including 13 previously identified loci and 16 newly identified sites (Table S2). When the CRP-binding sequences are located upstream or near promoters of the flanking genes, these genes are predicted to be under the control of CRP. eco mchibucos MI:0657 in vitro selection evidence