Immunoaffinity purification of the glycosylated extracellular fragment of mouse Plexin A2 produced in a mammalian expression system

Plexins are type I membrane proteins that function as receptors for semaphorins. All of the known plexins contain a large globular domain, termed the sema domain, in the N-terminal extracellular region, which interacts with semaphorins during signal transduction. Here, we describe procedures for protein production and purification that we utilized in the crystallographic study of the mouse Plexin A2 (mPlxnA2) extracellular fragment, including the sema domain. A mutant mammalian cell line, HEK293S GnTI−, was used as an expression host for the production of a crystallizable-quality mPlxnA2 fragment, which contains several N-glycosylation sites and disulfide bonds.