ZnT5a

ZnT5a is an isoform of the zinc transporter ZnT5, encoded by the SLC30A5 gene. It arises from alternative promoter usage and splicing to generate an N-terminally distinct variant, ZnT5a, in contrast to ZnT5b. Both ZnT5a and ZnT5b belong to the ZnT family, which transports Zn2+ from the cytosol into intracellular organelles such as the Golgi apparatus.

ZnT5a localizes primarily to the Golgi apparatus and other components of the secretory pathway, where it moves zinc into the lumen of these organelles. This zinc loading supports the maturation and proper function of zinc-dependent enzymes and secretory proteins that rely on zinc as a cofactor.

Expression of ZnT5a is broad across multiple tissues, with particularly important roles in organs that engage in extensive secretory activity, such as the pancreas and intestine. The activity of ZnT5a is influenced by cellular zinc status and can be affected by the regulatory context of promoter usage that generates the isoform.

Understanding ZnT5a contributes to a broader view of zinc allocation within the secretory pathway and the maintenance of intracellular zinc homeostasis. Disruptions in ZnT5a function can perturb zinc supply to organelles, potentially impacting protein processing and enzyme maturation that depend on zinc.