The role of the N terminus of GPIbβ in the coexpression of GPIX.

The N terminus of GPIbβ is essential for the coexpression of GPIX. Wildtype GPIbβ and wildtype GPIX were simultaneously cotransfected into HEK 293T cells (panels A, D). GPIbβ truncated at residues 14 (B, E) or 26 (C, F) were cotransfected into HEK293T cells with GPIX. Cells were then reacted with the anti-GPIX antibody FMC 25 (panels A-C) or the complex-specific antibody AK1 (panels D-F). N-terminal truncations of GPIbβ do not bring GPIX to the surface.