- A highly conserved protein family interacting with the fragile X mental retardation protein (FMRP) and displaying selective interactions with FMRP-related proteins FXR1P and FXR2P. Schenck, A., Bardoni, B., Moro, A., Bagni, C., Mandel, J.L. Proc. Natl. Acad. Sci. U.S.A. (2001)