Three alternatively spliced variants of the gene coding for the human bone morphogenetic protein-1.

The human bone morphogenetic protein-1 was originally identified as a protein with the capacity to stimulate bone and cartilage growth in vitro. Its gene sequence identified it as an alternatively spliced human homolog of the Drosophila dorsal-ventral patterning tolloid gene and suggested that it activates transforming growth factor-beta-like molecules by proteolytic cleavage. Its expression pattern and its recently identified activity as a procollagen C proteinase, however, suggest that it has a more general function in the early stages of embryogenesis. This view is strengthened by the previous observation of a third alternatively spliced isoform of the gene, called bone morphogenetic protein 1/His. We now show that the gene is expressed in three additional variants, leading to shorter and slightly modified C-termini. The three variants are preferentially expressed in placenta but show individual differences in their expression profiles in other soft tissues.