Linker region and the adjacent EF2 sequence of MCFD2 are not required for binding to FV and FVIII. (A) COS-1 cells were cotransfected with the D129E missense mutant or the indicated MCFD2 deletion mutants along with either FV (A) or FVIII (B). All deletion mutants also contain the D129E missense mutation. Cells were incubated with or without DSP before lysis. Cell lysates were immunoprecipitated with anti-myc (myc), anti-LMAN1 (L), and either anti-FV (F5 in panel A) or anti-FVIII (F8 in panel B) antibodies.