N-terminal domain of MCFD2 is not required for binding to FV and FVIII. COS-1 cells were cotransfected with the D129E missense mutant MCFD2 or N-terminal deletion mutants (Δ35 and Δ40) and FV (A) or FVIII (B). Both deletion mutants also contain a D129E missense mutation. Cells were metabolically labeled 20 hours after transfection, incubated with or without DSP before lysis. Cell lysates were immunoprecipitated with preimmune serum (pre), anti-myc (myc), anti-LMAN1 (L), and either anti-FV (F5 in panel A) or anti-FVIII (F8 in panel B) antibodies. Arrowheads indicate the endogenous MCFD2 bands.