Plays a role in the delivery of peptides to major histocompatibility complex (MHC) class I molecules; this occurs in a transporter associated with antigen processing (TAP)-independent manner. May play a role in taste signal transduction via ITPR3. May play a role during fertilization in pronucleus congression and fusion. Plays a role in maintaining nuclear shape, maybe as a component of the LINC complex and through interaction with microtubules. Interacts (via coiled-coil domain) with ITPR3. Interacts with SUN1 and SUN2. Interacts with microtubules. Colocalized with ITPR3 on the endoplasmic reticulum membrane. Expressed at high levels in pre B-cells, mature B-cells and pre T-cells. Expressed at low levels in mature T-cells and plasma B-cells. Expressed in germinal center B-cells, splenic marginal zone cells and B-cell lymphomas. Expressed in neuronal cells in the cerebral cortex, epithelial cells in tonsil, adrenal glands, zymogen-producing cells in the stomach and epithelial cells in seminal vesicles. The removal of the C-terminal lumenal domain occurs by proteolytic processing. Belongs to the IRAG2 family. It is uncertain whether Met-1 or Met-57 is the initiator methionine. However, according to PubMed:8021504, the initiator methionine is coded by a non-canonical CTG leucine codon; This leucine codon is in an excellent Kozak consensus located 39 bp upstream of the corresponding first mouse ATG. Wrong choice of frame. Truncated N-terminus.