Filamin A Interacting Protein 1 (FILIP1)

Using differential display, Nagano et al. (2002) identified Filip as a transcript responsible for initiating radial cell migration during neocortical development in embryonic rats. The deduced 1,212-amino acid protein contains 5 coiled-coil regions separated by 4 leucine zipper motifs. Nagano et al. (2002) also identified a short variant that lacks 247 N-terminal residues, including part of the first coiled-coil domain. Neither variant has a signal sequence or a transmembrane domain. In situ hybridization showed that Filip was expressed in the ventricular zone of embryonic rat neocortex. It was also expressed in muscle tissue, including heart. The short variant of rat Filip colocalized with F-actin along stress fibers upon transfection into COS-7 cells, whereas the long variant showed a more punctate distribution within the cytoplasm.