SYCN (syncollin) functions as a specific molecular chaperone in bacterial type III secretion systems, particularly in Yersinia species. SYCN forms a cytoplasmic complex with YscB that specifically binds to YopN, a key regulatory protein that controls Yop secretion 1. This SycN/YscB complex is essential for preventing premature secretion of virulence proteins in the presence of calcium and facilitating proper YopN translocation into host cells 2. The chaperone activity of SYCN requires both SycN and YscB proteins working together, as neither protein alone can effectively associate with YopN 1. SYCN is also required for the regulated secretion of YopN by overcoming negative regulatory signals that prevent entry into the type III secretion pathway 3. Beyond its bacterial role, SYCN has emerged as a potential biomarker for pancreatic cancer diagnosis, showing significant elevation in pancreatic ductal adenocarcinoma compared to healthy controls 4. When combined with CA19.9 and REG1B, SYCN demonstrates improved diagnostic performance for early-stage pancreatic cancer detection 4. Additionally, SYCN expression has been identified in transcriptomic analyses of grass carp growth regulation and pancreatic cancer prognosis 56.