Synaptojanin is a phosphatidylinositol phosphatase involved in clathrin-mediated endocytosis of synaptic vesicles. Synaptojanin 1 has two alternatively spliced isoforms; one that is ~ 145 kDA and is exclusively expressed in neurons, and the other ~ 170 kDa which is expressed in non-neuronal, peripheral tissues (Ramjaun AR & McPherson PS, 1996). The gene which encodes Synaptojanin 1, SYNJ1, has been mapped to chromosome 21 thus making it a candidate for involvement in Down
