ER protein VAP establish membrane contact sites VAP A intrinsically disordered regions enable versatile tethering at membrane contact sites: Developmental Cell Beyond Static Tethering at Membrane Contact Sites: Structural Dynamics and Functional Implications of VAP Proteins Structural and functional studies of the VAPB PTPIP51 ER mitochondria tethering proteins in neurodegenerative diseases Acta Neuropathologica Communications Springer Nature Link