Fig. 1. Sequence alignment of Sp-like proteins. (A) Comparison of the Sp8 orthologs from Tribolium and Drosophila. Serines and threonines are only moderately enriched and glutamine rich regions are not present in the deduced T-Sp8 protein. These regions are present in the Drosophila ortholog and are thought to be targets for post-translational modification (serines/threonines) or to be essential for transcriptional activation (glutamines) (Bouwman and Philipsen, 2002). (B) Alignment of the Btd-box and the adjacent zinc-finger region of different species; the cysteines (C) and histidines (H) structuring the zinc fingers are marked in green in A. (C) A comparison of the N-terminal Sp-box reveals a closer relationship of the insect sequences to Sp8 than to Sp7. The Sp-box is suggested to function in regulating the proteolysis of Sp factors or alternatively as a motif for interaction with a repressor (Bouwman and Philipsen, 2002).| indicates identical amino acid positions, - refers to gaps. Hs, Homo sapiens; Gg, Gallus gallus; Mm, Mus musculus; Rn, Rattus norvegicus.