IDENTIFICATION OF A NEW MEMBER OF TRANSFORMING-GROWTH-FACTOR-BETA SUPERFAMILY IN DROSOPHILA - THE FIRST INVERTEBRATE ACTIVIN GENE

Activins, a subgroup of the transforming growth factor-beta (TGP-beta) superfamily, have been extensively studied in vertebrates for their r oles in growth and development. However, activins are not thought to b e expressed in invertebrates. The identification of the first inverteb rate activin gene is reported here. A genomic clone representing 102 F region of the Drosophila chromosome 4 is found to encode a putative a ctivin beta. The predicted protein sequence has a multibasic protease site that would generate a mature C-terminal peptide containing 113 am ino acids showing >60% similarity to the vertebrate activin beta(B) (i nhibin beta(B)) sequences. A TGF-beta family signature as well as all 9 cysteine residues conserved in the vertebrate activins are also pres ent in this mature peptide sequence. Northern blot and RT-PCR analyses indicated that the activin beta gene is expressed in embryo, larva an d adult stages of Drosophila. (C) 1998 Academic Press.