Nuclear envelope protein which has essential roles in assembly of nuclear pore complexes and in chromatin maintenance during the cell cycle (PubMed:16950114, PubMed:16950115, PubMed:26166571, PubMed:27341616). Appears to be a stable structural component of the nuclear envelope during interphase (PubMed:16950114, PubMed:16950115). In dividing cells, localizes to kinetochores during early stages of mitosis and then to chromatin during late mitosis (PubMed:16950114, PubMed:27341616). Important for several mitotic processes including chromosome condensation, kinetochore assembly, chromosome segregation and cell-cycle timing (PubMed:16950114, PubMed:16950115, PubMed:26166571, PubMed:27341616). In postmitotic cells, plays a role in the early steps of nuclear pore complex assembly by recruiting the nucleoporins npp-10 and npp-5 to chromatin (PubMed:16950114, PubMed:16950115). Also involved in meiotic chromosome segregation (PubMed:27341616). May function downstream of the Ran GTPase signaling pathway (PubMed:16950115). Has a dynamic expression pattern during the cell cycle (PubMed:16950114, PubMed:27341616). During interphase, localizes to nuclear pore complexes and is also found in the nucleoplasm (PubMed:16950114, PubMed:27341616). During early mitosis, localizes to kinetochores in a hcp-3/CENP-A and hcp-4/CENP-C dependent manner (PubMed:16950114, PubMed:16950115, PubMed:27341616). At later stages of mitosis (anaphase), widely distributed on chromatin (PubMed:16950114, PubMed:27341616). During telophase, localizes again to the reforming nuclear envelope (PubMed:16950114, PubMed:27341616). Ubiquitously expressed (at protein level). Expressed at all stages of development. RNAi-mediated knockdown results in embryonic lethality (PubMed:16950114). Impairs assembly of the nuclear pore complex, the integrity of the nuclear envelope and distribution of the integral nuclear envelope proteins lmn-1, lem-2 and emr-1 and the nuclear pore complex proteins npp-9, npp-10 and npp-1 (PubMed:16950114, PubMed:16950115). Reduces the recruitment of npp-10 and npp-5 to chromatin (PubMed:16950114). Leads to hypercondensation and mispositioning of chromatin, defects in migration and positioning of the pronuclei, dissociation of centrosomes from chromatin, precocious centrosome separation, as well as defects in kinetochore assembly, spindle assembly, chromosome segregation and chromatin distribution in meiosis and mitosis (PubMed:16950114, PubMed:16950115). Impairs mitotic progression and leads to chromatin bridges (PubMed:16950114, PubMed:16950115). Reduces knl-3 localization to the kinetochores (PubMed:16950115). Suppresses the chromosome-decondensation defect in evl-18/cdc-45 mutant embryos (PubMed:26166571).