Protein S100-A13

S100-A13 is a small calcium-binding protein that facilitates the export of signal-peptide-lacking proteins through an alternative secretory pathway (UniProt: Q99584). It binds calcium and copper ions and is required for stress-induced secretion of cytokines and growth factors, particularly interleukin-1α and fibroblast growth factor 1. The protein interacts preferentially with phosphatidylserine-containing lipid vesicles, suggesting a role in membrane trafficking.

While UniProt reports no annotated disease associations for S100-A13, proteomic evidence links it to Alzheimer's disease pathology. In post-mortem Alzheimer's brain tissue compared to age-matched controls, S100-A13 is significantly upregulated (mean log2 fold-change: 0.61) as measured by mass spectrometry across subcellular fractions (Chaparral AD proteomics). This upregulation suggests altered secretory pathway activity or protein export dysregulation in AD neuropathology, potentially reflecting neuroinflammatory responses or changes in growth factor signaling that characterize the disease.