| Using the yeast two hybrid system and the in vitro GST pull down assay , we found that the N terminal proline / serine rich ( PS ) domain of ULK 1 ( amino acid 287 416 ) is required for ULK 1 GATE 16 and ULK 1 GABARAP protein interactions . ^^^ However , the kinase activity of ULK 1 affected neither ULK 1 GATE 16 nor ULK 1 GABARAP interaction . ^^^ Immunohistochemical analysis using ULK 1 and GABARAP antibodies showed that the ULK 1 and the GABARAP proteins co localized to many kind of neurons such as pyramidal cells of the hippocampus , mitral cells of the olfactory bulb , and Purkinje cells of the cerebellum . ^^^ In HeLa cells , endogenous ULK 1 and tagged GABARAP showed punctate structures in the cytosol , and were colocalized . ^^^ These results suggest that the interaction of ULK 1 and GABARAP is important to vesicle transport and axonal elongation in mammalian neurons . . ^^^ |