A presynaptic inositol-5-phosphatase.
McPherson, Peter S.; Garcia, Elizabeth P.; Slepnev, Vladimir I.; David, Carol; Zhang, Xiaomei; Grabs, Detlev; Sossin, Wayne S.; Bauerfeind, Rudolf; Nemoto, Yasuo; De Camilli, Pietro
[Letter] Nature. 379(6563):353-357, January 25, 1996.

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SYNAPTOJANIN is a nerve terminal protein of relative molecular mass 145,000 which appears to participate with dynamin in synaptic vesicle recycling *RF 1,2*. The central region of synaptojanin defines it as a member of the inositol-5-phosphatase family, which includes the product of the gene that is defective in the oculocerebrorenal syndrome of Lowe [3-7]. Synaptojanin has 5-phosphatase activity and its amino-terminal domain is homologous with the yeast protein Sac1 (Rsd1), which is genetically implicated in phospholipid metabolism and in the function of the actin cytoskeleton [8-10]. The carboxy terminus, which is of different lengths in adult and developing neurons owing to the alternative use of two termination sites, is proline-rich, consistent with the reported interaction of synaptojanin with the SH3 domains of Grb2 ( [1,2]). Synaptojanin is the only other major brain protein besides dynamin that binds the SH3 domain of amphiphysin, a presynaptic protein with a putative function in endocytosis [11-14]. Our results suggest a link between phosphoinositide metabolism and synaptic vesicle recycling.

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