Sec10p

Sec10p is a component of the exocyst complex in the budding yeast Saccharomyces cerevisiae. It is encoded by the SEC10 gene and participates in the orchestration of exocytosis, the process by which secretory vesicles are tethered to and docked at the plasma membrane to release their cargo.

The exocyst is an octameric protein complex that mediates the tethering of secretory vesicles to the plasma membrane as a prerequisite for SNARE-driven fusion. Sec10p contributes to this tethering function by associating with other exocyst subunits and coordinating the assembly of the complex at sites of secretion, thereby enabling polarized secretion during bud growth and cell surface remodeling.

Localization and interactions are key to Sec10p’s role. Sec10p localizes to the cortex of the growing bud and interacts with multiple exocyst components, including Sec6, Sec8, Sec5, Sec3, Sec15, Exo70, and Exo84. Its recruitment and activity are linked to the activity of the Rab GTPase Sec4p on vesicles, and the plasma membrane targeting involves interactions with cortical landmarks such as Sec3p and Exo70, which help define sites of secretion.

Genetic and functional data indicate that Sec10p is essential for efficient exocytosis and normal cell polarity in yeast. Mutations can cause accumulation of secretory vesicles, secretion defects, and growth abnormalities, reflecting the central role of Sec10p in vesicle trafficking.

Sec10p and the exocyst are broadly conserved across eukaryotes, with homologous subunits present in other fungi and in higher organisms. The basic mechanism of vesicle tethering by the exocyst underpins polarized secretion in diverse cell types.