SNX5 Human

SNX5 plays a crucial role in macropinocytosis, a specialized form of endocytosis that involves the uptake of extracellular fluid and solute molecules into large vesicles called macropinosomes. This process is essential for various cellular functions, including immune responses, cell motility, and nutrient uptake .

In macrophages, SNX5 has been shown to regulate the formation of macropinosomes derived from dorsal ruffles, which are actin-rich structures on the cell surface. Studies have demonstrated that SNX5-deficient macrophages exhibit a significant reduction in macropinocytic uptake, highlighting its importance in this pathway .

The phosphorylation of SNX5 at serine 226 is a critical regulatory mechanism that affects its function in membrane trafficking. Phosphorylation at this site influences the ability of SNX5 to form heterodimers with other sorting nexins, such as SNX1 and SNX2. This dimerization is essential for the retrograde trafficking of the cation-independent mannose 6-phosphate receptor (CI-M6PR) and the proper functioning of macropinocytosis .

SNX5 interacts with various proteins to mediate its functions. For instance, it has been observed to associate with newly formed macropinosomes induced by epidermal growth factor (EGF) stimulation. This interaction helps in tracking the maturation of macropinosomes and understanding the dynamics of membrane trafficking .

Macropinocytosis, regulated by SNX5, is vital for antigen sampling by antigen-presenting cells of the innate immune system. This process allows immune cells to capture and process antigens, facilitating the activation of adaptive immune responses. Therefore, SNX5 plays an indirect yet significant role in immune surveillance and defense mechanisms .