Multifunctional protein which functions as a renin, prorenin cellular receptor and is involved in the assembly of the lysosomal proton-transporting V-type ATPase (V-ATPase) and the acidification of the endo-lysosomal system. May mediate renin-dependent cellular responses by activating ERK1 and ERK2. By increasing the catalytic efficiency of renin in AGT/angiotensinogen conversion to angiotensin I, may also play a role in the renin-angiotensin system (RAS) (By similarity). Through its function in V-type ATPase (v-ATPase) assembly and acidification of the lysosome it regulates protein degradation and may control different signaling pathways important for proper brain development, synapse morphology and synaptic transmission (By similarity). Interacts with renin. Accessory component of the multisubunit proton-transporting vacuolar (V)-ATPase protein pump. Interacts (via N-terminus) with ATP6AP1 (via N-terminus). Interacts with ATP6V0D1; ATP6V0D1 is a V-ATPase complex subunit and the interaction promotes V-ATPase complex assembly. Interacts with TMEM9; TMEM9 is a V-ATPase assembly regulator and the interaction induces the interaction with ATP6V0D1. Interacts with VMA21 (via N-terminus); VMA21 is a V-ATPase accessory component. Phosphorylated. Proteolytically cleaved by a furin-like convertase in the trans-Golgi network to generate N- and C-terminal fragments.