Isolation of recombinant BMP receptor IA ectodomain and its 2 : 1 complex with BMP-2

Bone morphogenetic protein-2 (BMP-2) is a member of the transforming growth factor beta superfamily which induces bone formation and regeneration, and important steps during early embryonic development, BMP-2 signals via olig omerization of type I and type II serine/threonine kinase receptors, We rep ort here expression of the extracellular domain of the human type IA recept or for BMP-2 (BMPR-IA) in Escherichia coli. This soluble form of BMPR-IA (s BMPR-IA) was purified employing a BMP-2 affinity column, Cel filtration exp eriments and analysis of gel filtration fractions by polyacrylamide electro phoresis and densitometry reveal that BMP-2 forms a defined 1:2 complex wit h sBMPR-IA. that can be purified and hopefully used for crystallization stu dies. (C) 2000 Federation of European Biochemical Societies.