Involved in the remodeling of the cell wall during the various phases of yeast culture development and under various environmental conditions. Required for the maintenance of the CLB5 kinase activity. Non-covalently bound to the cell wall. Expression is repressed by anoxia. Expression is decreased during transition to slow growing or stationary phases. Leads to increased resistance to zymolyase treatment. Present with 1800 molecules/cell in log phase SD medium. Belongs to the SUN family.