Component of the type II secretion system inner membrane complex required for the energy-dependent secretion of extracellular factors such as proteases and toxins from the periplasm. Type II secretion system is composed of four main components: the outer membrane complex, the inner membrane complex, the cytoplasmic secretion ATPase and the periplasm-spanning pseudopilus (By similarity). Homodimer (By similarity). Interacts with XcpR/GspE and XcpY/GspL components (PubMed:17464073). Belongs to the GSP F family.