Considering that SGIP1 is a neuronal endocytotic protein interacting with adaptor proteins involved in clathrin-dependent endocytosis and that the SGIP1a has been implicated to play a role in endocytosis in neuronal cells, we tested whether calnexin may play any role in neuronal endocytosis. First, we examined whether GFP-SGIP1 affects uptake of transferrin in N1E-115 cells. Transferrin has been commonly used as an indicator of clathrin-dependent endocytosis. N1E-115 cells were transfected with either GFP-SGIP1 or GFP expression vectors, incubated with Alexa-transferrin, fixed and examined by confocal microscopy. As expected, expression of GFP in N1E-115 cells did not have any effect on transferrin uptake. In contrast, GFP-SGIP1 expressing cells had significantly inhibited transferrin uptake. Second, we asked whether clathrin-dependent endocytosis might also be affected in the absence of calnexin. Cerebellar granule cells were isolated from of 7 day old wild-type and calnexin-deficient mice. A mixed granule cell culture was established PF 05190457 containing wild-type and calnexin-deficient cells. One of the best described functions of calnexin is its role as a molecular chaperone. Little information is available about the structure and function of the cytoplasmic calnexin C-tail as the majority of studies on calnexin has focused on its ER luminal lectin-like chaperon domain. Here we showed that the calnexin C-tail is a potent inhibitor of endocytosis in neuronal cells indicating a functional specialization of calnexin domains. The Cterminal region of calnexin binds Ca2+ and can be phosphorylated by specific protein kinases and this enhances calnexin��s interactions with ribosomes. Ca2+ may affect endocytosis by the neuronal PF 04457845 system by arresting synaptic vesicle movement or increasing synaptic vesicle size. Absence of calnexin results in a severe neurological phenotype in mice manifested by impaired gait, reduced lower limb function and inhibited nerve conductive velocity due to impaired myelination of the peripheral and central nervous system. Increased endocytosis in the nervous system in the absence of calnexin as described in this study may also, at least in part, contribute to the phenotype of calnexindeficient mice. For example, endocytosis and postendocytic sorting of neurotransmitter receptors have emerged as critical mechanisms responsible for various forms of synaptic plasticity. Calnexin may affect these critical pathways and impact synaptic plasticity and consequently the function of the nervous system. This, at least in part, might be mediated by C-terminal cytoplasmic domain of calnexin. There are two major fractions in this extract: flavonoids and terpenes. Interestingly, these two have different properties which are responsible for exerting unique and diverse pharmacological actions of EGb761.