A MEMBER OF THE TGF-BETA RECEPTOR GENE FAMILY IN THE PARASITIC NEMATODE BRUGIA-PAHANGI

The full length cDNA sequence of a Type I transforming growth factor-b eta (TGF-beta) receptor has been isolated from the filarial parasitic nematode Brugia pahangi. This new gene, designated Bp-trk-1, encodes a predicted 645 amino acid sequence with an N-terminal hydrophobic stre tch which may act as a signal peptide. The extracellular portion (resi dues 15-187) is cysteine-rich and has three potential N-glycosylation sites. At positions 250-255 the protein contains the glycine-serine ri ch motif characteristic of Type I receptors. The closest homologue is a Caenorhabditis elegans gene (Q09488) in cosmid C32D5.2 which shares 67% amino acid identity with Bp-trk-1 in the most conserved kinase dom ain (aa 259-482). Other type I receptors such as C. elegans daf-1 and Drosophila tkv show 38-53% identity in the same region. Some residues conserved in Drosophila and vertebrates are not present in the B. paha ngi sequence. RT-PCR amplification has been used to show that the tran script is expressed in the three main stages of the B. pahangi life cy cle: microfilariae, infective larvae and adults. The ligand remains un known at this time but is likely to be most similar to that for C. ele gans Q09488. (C) 1997 Elsevier Science B.V.