FIGURE 8. Three-dimensional structure of the PCI domain in human eIF3k.

A, the N-terminal TPR/HAM subdomain is colored green, whereas the C-terminal WH subdomain is colored yellow. The described leucine residue corresponds to Leu¹²¹ (red) in eIF3k and is located at the end of the α3 helix in the N-terminal TPR/HAM subdomain. Three helices from the TPR-like subdomain and one helix from the WH subdomain (arrowheads) contain hydrophobic amino acid residues that may interact with Leu¹²¹ (see B). B, within a 5-Å radius from this leucine, at least 5 hydrophobic amino acids colored in purple (Leu¹⁰⁵, Phe¹¹⁷, Trp¹¹⁸, Leu¹²⁸, and Phe¹³⁴) can be readily identified that may interact with this leucine. We note that although most of these neighboring hydrophobic residues reside in the TPR/HAM domain, Phe¹³⁴ is in the WH domain. These images were created by Chimera (32) and PyMOL software.