Cytoplasmic FMR1-interacting protein 1

CYFIP1 (cytoplasmic FMR1-interacting protein 1) is a 145 kDa adapter protein that functions as a component of the CYFIP1-EIF4E-FMR1 complex, mediating translational repression by facilitating interactions between FMR1 and the mRNA cap-binding protein EIF4E (UniProt: Q7L576). The protein also regulates actin cytoskeletal dynamics as part of the WAVE complex, controlling membrane ruffles, lamellipodia formation, and axon outgrowth through interactions with Arp2/3 and RAC1.

CYFIP1 participates in multiple cellular processes including BDNF-NTRK2 endocytic trafficking from early endosomes and epithelial morphogenesis. The protein localizes to the cytoplasm and functionally bridges translation control and actin remodeling pathways critical for neuronal development and synaptic plasticity.

In Alzheimer's disease, CYFIP1 is significantly upregulated in post-mortem AD brain tissue compared to age-matched controls (mean log2 fold-change +0.59; Chaparral AD proteomics). This elevation was detected across subcellular fractions from TMT-labeled proteomic analysis, suggesting increased protein abundance may reflect altered translation regulation or cytoskeletal reorganization in the AD brain environment.