Molecular cloning, expression and characterization of the zebrafish bram1 gene, a BMP receptor-associated molecule

We have identified a cDNA clone encoding BMP receptor- associated molecule 1 ( BRAM1) from the zebrafish expressed sequence tag ( EST) database. The 2606 bp full- length bram1 cDNA was cloned, and further confirmed by nucleotide sequencing. The zebrafish sequence encodes a protein of 195 amino acids with an evolutionarily conserved MYND domain, which displays similar to 98% homology with human and mouse BRAM1, and similar to 64% homology with C. elegans BRA- 1 and BRA- 2. The bram1 gene, composed of five exons and four introns, spans similar to 14 kb on linkage group 14 of the zebrafish genome. RT- PCR and whole mount in situ hybridization analyses disclosed that zebrafish BRAM1 is a maternal factor. The protein interacts directly with zebrafish BMP Receptor type IA, as observed from GST- pull down and co- immunoprecipitation assays. Furthermore, cotransfection of zebrafish BRAM1 with the corresponding BMP receptor resulted in down- regulation of BMP- mediated signaling. Our results collectively indicate that BRAM1 plays a biological role during zebrafish development.