Localization of Rab27a mutations on Rab3A structure.

Ribbon representation of the Rab3A/GTP-bound structure with the putative switch regions highlighted in purple (switch 1) and yellow (switch 2), and the CDRs in blue. The amino acids mutated in Rab27a⁻ patients (Leu130Pro, Ala152Pro, and Trp73Gly) are indicated with an arrow at their equivalent positions on the Rab3A structure, Leu132 and Ala154 (in brown) and Trp76 (in red). The constitutively active (Gln78Leu) and inactive (Thr23Asn) Rab27a mutations are shown in green at their corresponding Rab3A residues, Gln81 and Thr36, respectively. Phe59 and Tyr91 (in pink) and Trp76 (in red) define the invariant hydrophobic triad.