Essential nuclear envelope (NE) integral membrane protein; role in NE fusion during biogenesis of the nuclear pore complex; Brr6p-Brl1p interaction proposed to drive membrane fusion by forming a channel across the bilayers enabling lipid exchange; interacts and functions with Apq12p and Brl1p in lipid homeostasis; role in maintaining architecture and transcriptional regulation at the NE through chromatin interaction; Brl1p homolog; functional homolog of metazoan CLCC1