In concert with ran, required for proper eye development. May be involved in the expression of early eye marker genes. Homooligomer. Interacts with banf1-a and banf1-b. Interacts with ran-gtp. Localization in the nuclear membrane is essential for its function. Colocalizes with and lamins and banf1-a/b at the nuclear envelope. The transmembrane domains are required and sufficient for its oligomerization. Phosphorylated. Belongs to the NEMP family.