Plant Molecular Biology

, Volume 46, Issue 1, pp 79–88 | Cite as

Identification of a cytoskeleton-associated 120 kDa RNA-binding protein in developing rice seeds

  • R. Sami-Subbu
  • Sang-Bong Choi
  • Yujia Wu
  • Changlin Wang
  • Thomas W. Okita


During rice seed development, prolamine RNAs are localized to the surface of the prolamine storage protein bodies (PBs), organelles bounded by the endoplasmic reticulum (ER). The exact mechanism by which prolamine RNAs are enriched on this ER subdomain is not known but recent evidence indicates the directed transport and targeting of prolamine RNAs to the prolamine PBs. As such a process involves RNA signal determinants and cytoskeleton-interacting proteins that recognize these signals, we obtained an enriched cytoskeleton-PB fraction and identified a prominent RNA-binding activity, Rp120, by RNA-binding UV-cross-linking assay. Recombinant cDNA clones of Rp120 revealed that the primary sequence shared considerable structural homology to the human transcriptional coactivator p100 and possessed a modular organization, four nucleic acid-binding SN domains, a tudor domain and a coil-coil domain. Consistent with the presence of SN domains, Rp120 binds a variety of RNAs including prolamine RNA. Interaction with the latter RNA, however, was specific as binding activity was evident only to the prolamine 3′ UTR and not to the 5′ UTR or coding sequences. Rp120 is also able to interact with other proteins as its sedimentation behavior in sucrose density gradient suggests an association with the cytoskeleton. The presence of a tudor domain, suggested to have a role in RNA processing or transport, together with the SN and coiled-coil domains are consistent with the view that Rp120 may be involved in RNA sorting in rice endosperm.

cytoskeleton protein bodies RNA-binding protein rice prolamine Rp120 


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Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • R. Sami-Subbu
    • 1
  • Sang-Bong Choi
    • 2
  • Yujia Wu
    • 2
  • Changlin Wang
    • 2
  • Thomas W. Okita
    • 2
  1. 1.National Chemical LaboratoryPuneIndia
  2. 2.Institute of Biological ChemistryWashington State UniversityPullmanUSA

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