Sec25p

Sec25p is a protein encoded by the SEC25 gene in the yeast Saccharomyces cerevisiae. It is a subunit of the coat protein complex II (COXIV), which is essential for the formation of transport vesicles that bud from the endoplasmic reticulum (ER). These vesicles carry cargo proteins from the ER to the Golgi apparatus for further processing and sorting. Sec25p plays a critical role in the assembly and function of the COXIV coat, contributing to the recognition and recruitment of cargo, as well as the membrane deformation and scission events required for vesicle budding.

The SEC25 gene is a single-copy gene located on chromosome IV. The Sec25p protein is a transmembrane protein with its N-terminus located in the ER lumen and its C-terminus in the cytoplasm. It interacts with other COXIV subunits, including Sec23p, Sec24p, and Sec13p, to form the functional COXIV complex. Genetic studies have shown that mutations in SEC25 lead to defects in ER to Golgi transport, resulting in the accumulation of proteins in the ER and impaired secretion. Sec25p is also involved in the regulation of the cell cycle and in response to cellular stress. Its precise molecular mechanisms of action are still under investigation, but it is known to be a key component of the COXIV machinery that drives the early stages of the secretory pathway in yeast.