Recombinant human ALK2 (PF197_198L) (activin receptor-like kinase-2), encompassing amino acids 147-end with a PF197_198L mutation (a.a. 197 (Pro) and 198 (Phe) were replaced with a single Leucine). This construct contains an N-terminal GST-tag. The recombinant protein was affinity purified and is active.