Identification of a Putative Invertebrate Helical Cytokine Similar to the Ciliary Neurotrophic Factor/Leukemia Inhibitory Factor Family by PSI-BLAST-Based Approach

School of Life Science, Fudan University, Shanghai, People's Republic of China.
Journal of interferon & cytokine research: the official journal of the International Society for Interferon and Cytokine Research (Impact Factor: 2). 07/2009; 29(8):461-8. DOI: 10.1089/jir.2008.0078
Source: PubMed


Most of our knowledge of helical cytokine-like molecules in invertebrates relies on functional assays and similarities at the physicochemical level. It is hard to predict helical cytokines in invertebrates based on sequences from mammals and vertebrates, because of their long evolutionary divergence. In this article, we collected 12 kinds of fish cytokines and constructed their respective consensus sequences using hidden Markov models; then, the conserved domains region of each consensus sequence were further extracted by the SMART tool, and used as the query sequence for PSI-BLAST analysis in Drosophila melanogaster. After two filtering processes based on the properties of helical cytokines, we obtained one protein named CG14629, which shares 25% identities/46% positives to fish M17 cytokine in the half length of the N-terminus. Considering the homology between M17 and LIF/CNTF (leukemia inhibitory factor/ciliary neurotrophic factor), and the close relationship between Dome, the putative cytokine receptor in Drosophila cells, and LIFR/CNTFR (LIF receptor/CNTF receptor), the results suggest that CG14629 is a good candidate for the helical cytokine ortholog in D. melanogaster.

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