Mode of action of the R2TP complex on the NAP57•SHQ1 complex. (A) The NAP57 extremities are required for S100-mediated release from SHQ1. SHQ1 bound to full-length (1–514, lane 3) or to NAP57 without its extremities (31–422, lane 4) was only released by S100 from the former (lane 5) but not the latter (lane 6). Histogram of the quantification of SHQ1 release relative to bound protein (below). (B) The C-terminal tail of NAP57 alone is required for S100-mediated SHQ1 release. SHQ1 bound to full-length NAP57 (1–514, lane 1), to NAP57 without N-terminal extremity (31–514, lane 2), without C-terminal tail (1–422, lane 3), and without both extremities (31–422, lane 4). S100 only released SHQ1 from NAP57 constructs with the C-terminal tail (lanes 5,6) but not from those without it (lanes 7,8). Note MBP-NAP57 lacking its C-terminal tail migrates as a single band (e.g., lanes 7,8). (C) Schematic summary of the results. See text for details.
