Guanine nucleotide exchange factor (GEF) regulating clathrin-mediated endocytosis through RAB35 activation. Promotes the exchange of GDP to GTP, converting inactive GDP-bound RAB35 into its active GTP-bound form. Regulates clathrin-mediated endocytosis of synaptic vesicles and mediates exit from early endosomes (PubMed:20154091, PubMed:20937701). Binds phosphatidylinositol-phosphates (PtdInsPs), with some preference for PtdIns(3)P (By similarity). The guanine nucleotide exchange factor (GEF) activity is autoinhibited. Autoinhibition may be the result of intramolecular interaction between the DENN domain and the C-terminus, which is disrupted upon phosphorylation. Activation is regulated by Akt activation. Interacts with RAB35 (PubMed:20154091). Interacts with clathrin and with the adapter protein complex 2, AP-2 (PubMed:20154091, PubMed:20937701). Interacts with ITSN1 AND SH3GL2 (By similarity). Interacts (when phosphorylated) with YWHAE (PubMed:26055712). Associates to membranes via lipid-binding activity. Phosphorylated on serine and/or threonine in an Akt-dependent manner. Phosphorylation probably regulates the guanine nucleotide exchange factor (GEF) activity, possibly by disrupting an intramolecular interaction between the DENN domain and the C-terminus of the protein, thereby relieving the autoinhibition. Genetic variants in DENND1A may play a role in susceptibility to polycystic ovary syndrome (PCOS), the most common endocrine disease among premenopausal women. PCOS is a complex disorder characterized by infertility, hirsutism, obesity, various menstrual disturbances, and enlarged ovaries studded with atretic follicles. Extended N-terminus. Extended N-terminus. Truncated N-terminus.