The C terminus of fragile X mental retardation protein interacts with the multi-domain Ran-binding protein in the microtubule-organising centre.
Absence of the fragile X mental retardation protein (FMRP) causes fragile X syndrome, the most common form of hereditary mental retardation. FMRP is a mainly cytoplasmic protein thought to be involved in repression of translation, through a complex network of protein-protein and protein-RNA interactions. Most of the currently known protein partners of FMRP recognise the conserved N terminus of the protein. No interaction has yet been mapped to the highly charged, poorly conserved C terminus, so far thought to be involved in RNA recognition through an RGG motif. In the present study, we show that a two-hybrid bait containing residues 419-632 of human FMRP fishes out a protein that spans the sequence of the Ran-binding protein in the microtubule-organising centre (RanBPM/RanBP9). Specific interaction of RanBPM with FMRP was confirmed by in vivo and in vitro assays. In brain tissue sections, RanBPM is highly expressed in the neurons of cerebral cortex and the cerebellar purkinje cells, in a pattern similar to that described for FMRP. Sequence analysis shows that RanBPM is a multi-domain protein. The interaction with FMRP was mapped in a newly identified CRA motif present in the RanBPM C terminus. Our results suggest that the functional role of RanBPM binding is modulation of the RNA-binding properties of FMRP.
Menon
Rajesh P
RP
National Institute for Medical Research, London NW7 1AA, UK. rmenon@nimr.mrc.ac.uk
Gibson
Toby J
TJ
Pastore
Annalisa
A
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002531:Cerebellum / Q000166:cytology; D002540:Cerebral Cortex / Q000166:cytology; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D051860:Fragile X Messenger Ribonucleoprotein 1; D005600:Fragile X Syndrome / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008607:Intellectual Disability; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011689:Purkinje Cells / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
D051860:Fragile X Messenger Ribonucleoprotein 1; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C497683:FMR1 protein, human