Protein preparation, crystallization and preliminary X-ray analysis of the C-terminal domain of human RSK1 serine/threonine protein kinase

As a substrate of extracellular signal-related kinase (ERK), the p90 ribosome S6 kinase 1 (RSK1) is at the terminus of the Ras/ERK pathway. Residues 411–735 of human RSK1, covering the C-terminal serine/threonine kinase catalytic domain and the functionally important tail, were cloned into an Escherichia coli expression vector. The protein was expressed, purified and crystallized. The crystals diffracted to 2.7 Å and belonged to space group P2₁, with unit-cell parameters a = 39.8, b = 143.8, c = 59.9 Å, β = 95.7°.