Fig. 5. Amino-acid sequence of WSP-1. (A) Amino-acid sequences of WSP-1 (C. elegans N-WASP) isoforms 1 and 2 are given with domains indicated by underlining. The sequence of WSP-1 isoform 2 continues to amino acid 171 of WSP-1 isoform 1. The asterisk in isoform 2 indicates the putative first methionine found in the cDNA sequence. It is possible that isoform 2 contains additional amino acids upstream of the sequence presented. (B) Domain structures of WSP-1 isoform 1 and 2. The splicing variant point is indicated with an arrowhead, and the bar indicates 100 amino acids. WH1, WASP homology 1 domain; CRIB, Cdc42/Rac interactive binding region; V, verprolin homology (VPH) domain; C, cofilin homology domain; A, acidic region. (C) Western blotting of mixed stage C. elegans lysates with an anti-WSP-1 antibody. A single band at 64 kDa is indicated with an arrowhead, indicating specific recognition of WSP-1 by the anti-WSP-1 antibody. (D) Activation of Arp2/3-complex-mediated actin polymerization by WSP-1. The actin polymerization assay using 60 nM bovine Arp2/3 complex and either 100 nM WSP-1 VCA or bovine N-WASP VCA. G-actin was added to a final concentration of 2 µM (9% pyrene-labeled).