The S1 domain is a protein domain that was originally identified in ribosomal protein S1 but is found in a large number of RNA-associated proteins. The structure of the S1 RNA-binding domain from the Escherichia coli polynucleotide phosphorylase has been determined using NMR methods and consists of a five-stranded antiparallel beta barrel. Conserved residues on one face of the barrel and adjacent loops form the putative RNA-binding site.
The structure of the S1 domain is very similar to that of cold shock proteins. This suggests that they may both be derived from an ancient nucleic acid-binding protein.
^Schubert M, Edge RE, Lario P, et al. (July 2004). "Structural characterization of the RNase E S1 domain and identification of its oligonucleotide-binding and dimerization interfaces". J. Mol. Biol. 341 (1): 37–54. PMID15312761. doi:10.1016/j.jmb.2004.05.061.
^ abcBycroft M, Hubbard TJ, Proctor M, Freund SM, Murzin AG (January 1997). "The solution structure of the S1 RNA binding domain: a member of an ancient nucleic acid-binding fold". Cell. 88 (2): 235–42. PMID9008164. doi:10.1016/S0092-8674(00)81844-9.