Mps3

Mps3 is a gene in the budding yeast Saccharomyces cerevisiae that encodes a SUN-domain protein located in the inner nuclear membrane. The Mps3 protein localizes to the spindle pole body (SPB) and the nuclear envelope, and it plays a key role in SPB duplication and in maintaining nuclear architecture during cell division.

As a member of the SUN-domain protein family, Mps3 forms part of a nuclear envelope bridge that connects chromatin to the cytoskeleton across the nuclear envelope. The C-terminal SUN domain resides in the perinuclear space, while the N-terminal region projects into the nucleoplasm and participates in chromatin-related functions. This arrangement positions Mps3 as an interface between the nuclear interior and the cytoskeletal apparatus.

In meiosis, Mps3 participates in telomere dynamics by interacting with meiosis-specific factors such as Ndj1 and Csm4 to tether telomeres to the nuclear envelope and to promote telomere-led chromosome movements essential for homologous pairing and recombination. In mitotic growth, Mps3 contributes to proper SPB duplication and spindle assembly; defects in Mps3 can lead to abnormal spindle formation and chromosome segregation errors.

Broader context places Mps3 within the conserved family of SUN-domain proteins that, together with KASH-domain partners in other organisms, form the LINC complex that couples the nucleoskeleton to the cytoskeleton. While the specifics of the yeast Mps3 interactions differ from vertebrate systems, the protein serves as an important model for understanding nuclear envelope–associated processes, chromatin organization, and chromosome dynamics.