Fig. 1. A family of evolutionary conserved EFA6-related proteins. (A) Predicted amino acid sequence of EFA6B. Regions corresponding to the Sec7 domain, the PH domain and the putative coiled-coil motif at the C-terminus are highlighted in yellow, green and purple, respectively. The predicted coiled-coil motif was identified using COILS (Lupas et al., 1991). (B) The Sec7 domains of human ARNO (Chardin et al., 1996), EFA6A (Perletti et al., 1997), EFA6C [AL136559 (Wiemann et al., 2001)], EFA6B (this study), EFA6D [KIAA0942 (Nagase et al., 1999)], ARF-GEP₁₀₀ (Someya et al., 2001), D. melanogaster CG6941, C. elegans Y55D9A.1 and S. cerevisiae Sec7 (Achstetter et al., 1988) were aligned using Clustal W (Thompson et al., 1994). The 10 helices (denoted A-J) of the ARNO Sec7 domain crystal structure are shown (Cherfils et al., 1998; Goldberg, 1998). Invariant and conserved residues are highlighted in green and yellow, respectively. Two highly conserved regions that together form the active site are underlined and denoted Motif 1 and Motif 2. The invariant glutamate residue in Motif 1 is highlighted in blue. Conserved residues in EFA6 family proteins are highlighted in purple, whereas conserved residues in other ARF GEFs that diverge in EFA6 family members are shown in red. (C) Sec7 domains were aligned using Clustal W and a phylogenetic-type tree was calculated from the alignment using NJplot (Perriere and Gouy, 1996; Thompson et al., 1994).

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