This superfamily consists of an RRM (RNA recognition motif) domain found in RNA binding proteins such as hnRNP proteins (heterogeneous nuclear ribonucleoproteins), in the ribosomal protein L23 in prokaryotes INTERPRO:IPR019985, proteins implicated in regulation of alternative splicing (SR, U2AF, Sxl), protein components of small nuclear ribonucleoproteins (U1 and U2 snRNPs), and proteins that regulate RNA stability and translation (PABP, La, Hu), and a few single stranded DNA binding proteins. The RRM domain consists of four anti-parallel beta-strands and two alpha-helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases. hnRNPs are involved in regulation of alternative splicing, and protein components of snRNPs.

Pfam [PfamClan:CL0221], PFAM:PF00076, INTERPRO:IPR000504, INTERPRO:IPR035979,PMID:8290338