Identification of an RNA-binding domain in human SRP72

Elena Iakhiaeva, Jiaming Yin, Christian Zwieb

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


The signal recognition particle (SRP) is a ribonucleoprotein complex that plays a crucial role during the delivery of secretory proteins from the ribosome to the cell membrane. Among the six proteins of the eukaryotic SRP, the 72 kDa protein (SRP72) is the largest and least characterized. Polypeptides corresponding to various regions of the entire human SRP72 sequence were expressed in Escherichia coli, purified, and partially proteolyzed. Human SRP RNA bound with high affinity to a 63 amino acid residue region near the C terminus of SRP72. Mild treatment of the fragment with chymotrypsin abolished its RNA-binding activity. A conserved sequence with the consensus PDPXRWLPXXER was identified within a 56 amino acid residue RNA-binding domain. Sucrose gradient centrifugation and filter-binding analysis using mutant SRP RNAs showed that SRP72 bound to the moderately conserved portion of SRP RNA helix 5. Nine tetratricopeptide-like repeats (TPRs) poised to interact with other SRP or ribosomal proteins were predicted in the NH2-terminal region. These identifications assign two important functions to a large portion of SRP72 and demonstrate the RNA-binding capacity of the protein.

Original languageEnglish (US)
Pages (from-to)659-666
Number of pages8
JournalJournal of Molecular Biology
Issue number4
StatePublished - Jan 28 2005
Externally publishedYes


  • RNA-protein interactions
  • SRP
  • TPR
  • signal recognition particle
  • site-directed mutagenesis

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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