LAMP2 Antibody (YA309),MedChemexpress,HY-P80208

CD107b is a lysosomal membrane glycoprotein that plays a crucial role in lysosome biogenesis, lysosomal pH regulation, and autophagy. It acts as a key regulator of lysosomal lumen pH by directly inhibiting the proton channel TMEM175, facilitating lysosomal acidification for optimal hydrolase activity. CD107b is essential for chaperone-mediated autophagy, a process that mediates lysosomal degradation of proteins under stress conditions and during the normal turnover of long-lived proteins. It functions by binding target proteins such as GAPDH, NLRP3, and MLLT11, directing them for lysosomal degradation. In chaperone-mediated autophagy, CD107b operates downstream of chaperones like HSPA8/HSC70, which recognize and recruit substrate proteins to lysosomes, where they bind to LAMP2. Additionally, CD107b is involved in lysosomal protein degradation during starvation (by similarity) and mediates the fusion of autophagosomes with lysosomes during autophagy. Cells lacking LAMP2 fail to accumulate STX17 on autophagosomes, likely explaining the impaired fusion process. CD107b also contributes to MHC class II-mediated presentation of exogenous antigens by facilitating lysosomal protein degradation, generating antigenic peptides captured by MHC II subunits. However, it is not required for the presentation of endogenous antigens. Furthermore, CD107b supports FURIN-mediated cleavage of the mumps virus fusion protein F by interacting with both FURIN and the unprocessed form of the viral protein F.