Fig. 9. Overall organization of EFA6 family GEFs. Alignment of the Sec7 domain, PH domain and C-terminal region sequences. (A) A schematic structure of the EFA6 family and ARNO GEFs. Sec7 domains, PH domains and putative coiled-coil motifs are depicted by red, blue and yellow boxes, respectively. (B) Amino-acid sequences of the PH domains of human EFA6 family members, D. melanogaster CG6941 gene product, C. elegans Y55D9A. 1 and human beta IV 1 spectrin (Berghs et al., 2000) were aligned using Clustal W. Conserved residues in the seven PH domains are highlighted in green. Residues of the spectrin PH domain involved in interactions with inositol (1,4,5)P₃ phosphates (Hyvonen et al., 1995), and which are conserved in EFA6 family PH domains, are shown in bold. Invariant or similar residues amongst EFA6 family PH domains are highlighted in blue. (C) Amino-acid sequences of the conserved C-terminal regions of EFA6-family GEFs were aligned using Clustal W. Invariant residues are highlighted in green. Putative coil-coiled motifs identified using COILS are underlined. The terminus of C-terminal deletion variants of EFA6A (designed CT1 to 4) is indicated by an exclamation mark.