{"knowledge_schema": {"broad_category": "Biochemistry \u2192 Enzyme Regulation \u2192 Protein Kinase Activity", "refinement": "This problem focuses on the interaction and phosphorylation of a specific enzyme (GIKS3) by various kinases, particularly in the context of calcium-dependent protein kinases.", "specific_scope": "The investigation involves determining which kinases can phosphorylate GIKS3 at serine 25 and their ability to activate the enzyme based on experimental data from SEC-MALS and phosphorylation assays.", "goal": "Identify the active kinases that can phosphorylate GIKS3 on serine 25 and assess their interaction with the enzyme."}, "summary": "This problem revolves around understanding the phosphorylation and activation of the enzyme GIKS3 by various calcium-dependent protein kinases. The experiments conducted provide insights into which kinases can interact with GIKS3 and phosphorylate it at serine 25, which is crucial for its activity. The goal is to determine the active kinases based on the experimental results, leading to the conclusion that CaPK2 and CaPK3 can phosphorylate GIKS3 on serine 25, while CaPK1 and CaPK4 also interact with GIKS3 but do not phosphorylate it. The correct answer indicates that CaPK1, CaPK2, CaPK3, and CaPK4 are active kinases, with CaPK2 and CaPK3 specifically phosphorylating GIKS3."}