Essential role for KH domains in RNA binding: Impaired RNA binding by a mutation in the KH domain of FMR1 that causes fragile X syndrome

Haruhiko Siomi, Mleyoung Choi, Mikiko C. Siomi, Robert L. Nussbaum, Gideon Dreyfuss

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353 Citations (Scopus)


The KH domain is an evolutionarily conserved sequence motif present in many RNA-binding proteins, including the pre-mRNA-binding (hnRNP) K protein and the fragile X mental retardation gene product (FMR1). We assessed the role of KH domains in RNA binding by mutagenesis of KH domains in hnRNP K and FMR1. Conserved residues of all three hnRNP K KH domains are required for its wild-type RNA binding. Interestingly, while fragile X syndrome is usually caused by lack of FMR1 expression, a previously reported mutation in a highly conserved residue of one of its two KH domains (IIe-304→Asn) also results in mental retardation. We found that the binding of this mutant protein to RNA is severely impaired. These results demonstrate an essential role for KH domains in RNA binding. Furthermore, they strengthen the connection between fragile X syndrome and loss of the RNA binding activity of FMR1.

Original languageEnglish
Pages (from-to)33-39
Number of pages7
Issue number1
Publication statusPublished - 1994 Apr 8
Externally publishedYes


ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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