Fidgetin (FIGN)

The mouse mutation 'fidget' arose spontaneously in a heterogeneous albino stock. This mutant mouse is characterized by a side-to-side head-shaking and circling behavior, due to reduced or absent semicircular canals . Fidget mice have small eyes, associated with cell cycle delay and insufficient growth of the retinal neural epithelium. They also have lower-penetrance skeletal abnormalities, including pelvic girdle dysgenesis, skull bone fusions, and polydactyly. The fidget mutation had been mapped to mouse chromosome 2 . AAA proteins are molecular chaperones that facilitate a variety of functions, including membrane fusion, proteolysis, peroxisome biogenesis, endosome sorting, and meiotic spindle formation. the fidget mutation in the mouse was due to a retrotransposon insertion in intron 2, interfering with normal RNA processing.