S100A13

S100A13 Full Name

S100 calcium binding protein A13

S100A13 Introduction

S100A13 is a small calcium-binding protein of the S100 family, distinguished from most other S100 proteins by its unusual affinity for copper(II) and zinc(II) and by its involvement in the non-classical secretion of signal-peptide-less cytokines and growth factors. The protein is expressed in a wide range of tissues but is enriched in cells of mesenchymal origin, in the placenta, and in several carcinomas. Its gene sits within the S100 cluster on chromosome 1q21, a region prone to rearrangements in tumors and in inflammatory conditions.

Figure 1. The structure of S100A13.

Non-Classical Protein Secretion and Metal Binding
S100A13 binds Ca(II) with relatively low affinity but shows high-affinity binding for Cu(II) and Zn(II), properties that enable it to participate in the copper-dependent externalization of FGF1, IL-1α, and several other leaderless cargoes. On stimulation, S100A13 forms a multiprotein complex with FGF1 and the p40 Syt1-syntaxin-interacting protein, which is then translocated across the plasma membrane through a process that depends on Cu(II) binding and on lipid-raft integrity. S100A13 is itself secreted along with these factors, allowing it to act extracellularly as a damage-associated molecular pattern (DAMP) that engages RAGE and other receptors.

Cancer and Inflammatory Disease
S100A13 is overexpressed in several malignancies, including pancreatic, breast, and gastric cancer, where its co-secretion with FGF1 supports autocrine growth and angiogenesis. Plasma S100A13 levels have been proposed as biomarkers of tumor burden and of response to antiangiogenic therapy, since S100A13 secretion parallels that of its FGF1 cargo. In chronic inflammatory conditions such as rheumatoid arthritis and inflammatory bowel disease, extracellular S100A13 acts as a DAMP and contributes to sustained inflammation, and S100A13-blocking peptides have shown efficacy in preclinical models.

Alternate Names for S100A13

S100A13; S100 calcium binding protein A13; protein S100-A13; S100 calcium-binding protein A13;