Involved in seedling development in the dark. May be involved, when interacting with TSK, in the organization of spindle microtubules and may participate, when interacting with GIP1, in structural links between the nuclear envelope and the cytoskeleton. Homomultimer. Interacts (via C-terminal domain) with GIP1, CSN1 (via N-terminal domain) and TSK (via TPR repeats). In interphase, found in ER bodies and at the nuclear envelope (PubMed:24348487). During mitosis, concentrates in limited areas close to the ends of spindle microtubules ahead of separating chromatids (PubMed:15964904). Expressed preferentially in flowers and shoot apex. Up-regulated by wounding and jasmonic acid treatment. Contains a N-terminal NAI2 domain (474-759). Binds calcium through the EFE repeats.