Cytoplasmic FMR1 Interacting Protein 1 (CYFIP1)

CYFIP1 contains 1,253 amino acids and shares 88% sequence identity with CYFIP2. CYFIP1 and CYFIP2 are members of a highly conserved protein family and share approximately 99% sequence identity with their mouse orthologs.The deduced protein contains 1,271 amino acids. Northern blot analysis detected CYFIP1 expression in all human tissues and cell lines examined. Highest expression was in lung, kidney, spleen, prostate, and ovary, as well as in HeLa cells and KG-1 cells.CYFIP1 interacts exclusively with FMRP, whereas CYFIP2 also interacts with the FMRP-related proteins FXR1P and FXR2P. The interaction of FMRP and CYFIP involves the domain of FMRP that also mediates homo- and heteromerization, suggesting a competition between interaction among the FXR proteins and interaction with CYFIP.