Fig. 1. Sequence features of Kringelchen (GenBank Accession Number, AY193769). (A) Proposed structure and full-length sequence: features and their corresponding amino acid positions are given. The partial sequence of splice leader B is underlined. The amino acid sequence contains a signal peptide (boxed and italic), a transmembrane domain (boxed and bold) and an intracellular kinase domain (boxed only). Ig-like loop I and Ig-like loop II are boxed and shaded, and the sequence between Tyr 250 and Phe324 (corresponding to Ig-like loop III) is shaded only. The highly conserved cysteines, which form the Ig-like loops I and II are boxed and shaded. SH2 and SH3 domain-binding consensuses are bold and underlined, bold tyrosines correspond to crucial autophosphorylated tyrosines in vertebrate FGFR. (B,C) Alignment of the Hydra sequence corresponding to the first, second and third putative Ig-like loops with vertebrate and invertebrate FGFR. (B) Ig-like loop I (D1), (C) Ig-like loop II (D2; upper part of the figure) and Ig-like loop III (D3; lower part of the figure). a, acidic amino acid; b, basic amino acid; r, aromatic amino acid. (D) Intracellular (kinase) domain. Underlined is a potential SH2-binding site; (auto)phosphorylation sites (identified in vertebrate FGFR) are marked with +. Shortcuts and Accession Number for the used sequences are: Hy, Hydra vulgaris Kringelchen (AY193769); Ce, C. elegans Egl 15 (AAC46934); Bl and Hl, Drosophila Breathless (Q09147) and Heartless (Q07407); F1-F4, human FGFR 1-4 (P11362, P21802, P22607, P22455).