# p31Comet Splice Variants Induce Distinct Spindle Assembly Checkpoint Dynamics due to Their Unique N-Termini

## TL;DR

Two versions of a protein called p31Comet behave differently in cell division, with one version being less effective and more unstable, especially in the testes.

## Contribution

The study reveals that the N-terminal region of p31Comet splice variants affects their function in mitosis and stability.

## Key findings

- Variant 1 of p31Comet has reduced binding to MAD2 and slower mitotic progression compared to Variant 2.
- Variant 1 is less stable than Variant 2 and is uniquely expressed in the testes.
- The N-terminus of p31Comet modulates its activity during mitosis.

## Abstract

The role of p31Comet in deactivating the spindle assembly checkpoint is well described in the literature; however, the data are all completed using Variant 2 of p31Comet. p31Comet is known to be expressed as two different splice variants: Variant 1 and Variant 2. Variant 1 contains an additional 32 N-terminal residues compared to Variant 2. We report that Variant 1 exhibits a reduced ability to bind to MAD2 and thus a reduced ability to induce mitotic progression. Additionally, we show that Variant 1 exhibits reduced stability compared to Variant 2. We further show that Variant 1 is uniquely expressed in the Testes, indicating a potentially unique role of Variant 1 in that organ. Overall, we demonstrate the N-terminus of p31Comet is capable of modulating p31Comet activity in mitosis.