The S1 domain occurs in a wide range of RNA associated proteins. It is structurally similar to cold shock protein which binds nucleic acids. The S1 domain has an OB-fold structure.

1: The solution structure of the S1 RNA binding domain: a member of an ancient nucleic acid-binding fold. Bycroft M, Hubbard TJ, Proctor M, Freund SM, Murzin AG; Cell 1997;88:235-242. PMID:9008164