ACVRL1, also known as serine/threonine-protein kinase receptor R3, is a membrane-anchored proteoglycan whose core protein binds TGFf3 and has a short cytoplasmic domain with no discernible signaling structure. Also, this protein shares similar domain structures with other closely related ALK or activin receptor-like kinase proteins that form a subfamily of receptor serine/threonine kinases. Recombinant human ACVRL1, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.