A Jackson Laboratory research team led by Professor Patsy Nishina, Ph.D., has identified a mutation（突变） in a gene that's essential for correct protein-processing in cells. Defects in protein folding are associated with a variety of abnormalities and diseases. Cells don't come prefabricated（预制的） , with pieces plunked down and tacked together like modular（模块化的） homes offloaded from trucks. The structural proteins that give cells shape, tubulin（微管蛋白） and actin (think beams and girders), are themselves subject to essential processing before they become part of the assembly. Proteins must be folded in very specific ways to function properly, and depend on "chaperone" proteins to help them in the process. Defects in the chaperone（伴侣蛋白） proteins lead to disruption of the folding process, which adversely affects cellular development and growth.

The chaperones themselves, such as prefoldin（前折叠素） , are quite complicated. Prefoldin, which stabilizes brand new proteins, has six subunits assembled into a structure that looks like a jellyfish. Nishina and colleagues identified a mutation in one of the subunits of prefoldin, Pfdn5. In mice, it causes photoreceptor degeneration in the eye, central nervous system abnormalities and male infertility. Although Pfdn5 is widely expressed in other tissues, its disruption appears to significantly affect only these cells. Defects in other subunits disrupt development in other tissues, indicating that each prefoldin subunit is important for the processing of different proteins in different tissues.

The complex protein transport and folding process is only beginning to be fully studied in mammals. Given that disruptions in the process contribute to a variety of human disease mechanisms, the Pdfn5 mutation will be a valuable tool for further research.