The F-BAR (FES-CIP4 Homology and Bin/Amphiphysin/Rvs) domain of Fes (feline sarcoma) and Fer (Fes related) tyrosine kinases
F-BAR domains are dimerization modules that bind and bend membranes and are found in proteins involved in membrane dynamics and actin reorganization. Fes (feline sarcoma), also called Fps (Fujinami poultry sarcoma), and Fer (Fes related) are cytoplasmic (or nonreceptor) tyrosine kinases that play roles in haematopoiesis, inflammation and immunity, growth factor signaling, cytoskeletal regulation, cell migration and adhesion, and the regulation of cell-cell interactions. Although Fes and Fer show redundancy in their biological functions, they show differences in their expression patterns. Fer is ubiquitously expressed while Fes is expressed predominantly in myeloid and endothelial cells. Fes and Fer contain an N-terminal F-BAR domain, an SH2 domain, and a C-terminal catalytic kinase domain. F-BAR domains form banana-shaped dimers with a positively-charged concave surface that binds to negatively-charged lipid membranes. They can induce membrane deformation in the form of long tubules. The F-BAR domain of Fes is critical in its role in microtubule nucleation and bundling.