[Fragile X mental retardation protein interacts with human NDK/Nm23-H2]

To investigate the physiological role of fragile X mental retardation protein (FMRP) and screen the proteins interacting with FMRP in human fetal hippocampus cDNA library.

Human fetal hippocampus cDNA library was constructed in yeast two-hybrid DAD vector pGAD10. Quality of the library was measured by picking up random colonies as templates for PCR testing. Proteins interacting with FMRP were screened by yeast two-hybrid system. Furthermore, the interaction site of FMRP was mapped in yeast.

The average length of inserts of the two-hybrid library was 1.5 kb, and the ratio of recombinant colonies was about 90%. Human NDK/Nm23-H2 was found interacting with FMRP. NDK/Nm23-H2 interacted with FMRP exon 1-12, as well as FMRP isoforms without exon 12, and exons 14-17. NDK/Nm23-H2 couldn't interact with FMRP exon 1-6 and exon 2-7 fragments.

Human NDK/Nm23-H2 can bind FMRP directly. The interaction site of FMRP is located at its exon 1-11. This interaction in vitro might alter the intracellular distribution of NDK/Nm23-H2, and even regulates the transcription and expression of FMRP.