A novel nucleoskeletal-like protein located at the nuclear periphery is required for the life cycle of Saccharomyces cerevisiae.

In order to study the role of nucleoskeletal components for nuclear and cell division in the budding yeast Saccharomyces cerevisiae, we have employed a combined biochemical/genetic approach. We have identified a peripheral nuclear protein which appears to be located both at the nuclear membrane and the spindle pole body. The gene has been cloned and subsequently shown to be essential for cell growth. The DNA sequence of the gene has been determined. As deduced from the nucleotide sequence, the gene potentially codes for a novel 86 kd protein with a highly repetitive and conserved nine amino acid sequence motive in the middle part of the protein. The flanking amino- and carboxy-terminal regions have similarities to intermediate filaments and calcium binding proteins, respectively. It appears that the 86 kd protein is a regulated nucleoskeletal-like protein (NSP1) involved in the process of nuclear and/or cell division. The affinity-purified antibody against the yeast NSP1 protein stained the nucleus and centrosomes of mammalian MDCK (Madin Darby canine kidney) cells in indirect immunofluorescence.