Inner membrane component of the type II secretion system required for the energy-dependent secretion of extracellular factors such as proteases and toxins from the periplasm. Plays a role in the complex assembly and recruits XcpZ resulting in a stable complex in the inner membrane. Provides thus a link between the energy-providing XcpR protein in the cytoplasm and the rest of the T2SS machinery. 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). Forms homodimers (PubMed:30425318). Interacts with XcpZ/GspM (PubMed:9884230, PubMed:11872731, PubMed:16168578, PubMed:30337370). Interacts with XcpR/GspE and XcpS/GspF (PubMed:16168578). Absence of XcpY results in decreased amount of XcpZ in type II secretion system complexes. Belongs to the GSP L family.