Lysosomal membrane glycoprotein which plays a role in the unfolded protein response (UPR) that contributes to protein degradation and cell survival during proteasomal dysfunction. Plays a role in the process of fusion of the lysosome with the autophagosome, thereby modulating the autophagic process. Promotes hepatocellular lipogenesis through activation of the PI3K/Akt pathway. May also play a role in dendritic cell function and in adaptive immunity.