The Giant Protein AHNAK Is a Specific Target for the Calcium- and Zinc-binding S100B Protein

摘要: Transformation of rat embryo fibroblast clone 6 cells by ras and temperature-sensitive p53val135 is reverted ectopic expression the calcium- zinc-binding protein S100B. In an attempt to define molecular basis S100B action, we have identified giant phosphoprotein AHNAK as major most specific Ca2+-dependent target in cells. We next characterized a glial C6 human U-87MG astrocytoma cell lines. binds S100B-Sepharose beads also recovered anti-S100B immunoprecipitates strict Ca2+- Zn2+-dependent manner. Using truncated fragments, demonstrated that domains responsible for interaction with correspond repeated motifs characterize molecule. These show no binding calmodulin or S100A6 S100A11. provide evidence 2 Zn2+ equivalents/mol enhances S100B-AHNAK effect relies on regulation affinity Ca2+. Taking into consideration implicated calcium flux regulation, propose may participate S100B-mediated cellular Ca2+ homeostasis.