Potential guanine nucleotide exchange factor (GEF). GEF proteins activate some small GTPases by exchanging bound GDP for free GTP. Its interaction with presenilin proteins as well as its ability to stimulate Tau/MAPT phosphorylation suggest that it may be involved in Alzheimer disease. Ectopic expression in nerve cells decreases the secretion of amyloid-beta APBA1 protein and lowers the rate of cell- substratum adhesion, suggesting that it may affect the function of some small GTPase involved in the regulation of actin cytoskeleton or cell adhesion receptors (By similarity). . This is the function of DOCK3 (dedicator of cytokinesis 3, ENSG00000088538).