The spindle-associated transmembrane protein Axs identifies a new family of transmembrane proteins in eukaryotes

Axs mutations disrupt both the progression of the meiotic cell cycle and meiotic chromosome segregation in Drosophila. Axs protein co-localizes with endoplasmic reticulum components and is present within a novel structure ensheathing the meiotic spindle. We show that Axs encodes the founding member of a eukaryotic family of trans-membrane proteins.