Endoplasmic reticulum (ER)-shaping membrane protein that plays a role in determining ER morphology. Involved in the stabilization of nascent three-way ER tubular junctions within the ER network. May also play a role as a curvature-stabilizing protein within the three-way ER tubular junction network. May be involved in limb development (By similarity). Is involved in central nervous system development. Enables identical protein binding activity. Involved in endoplasmic reticulum tubular network maintenance and positive regulation of endoplasmic reticulum tubular network organization. Located in endoplasmic reticulum tubular network membrane and nucleoplasm. Is integral component of endoplasmic reticulum membrane.