The invention relates to a glycoprotein comprising an optionally fucosylated glycan according to formula (105) or (106), wherein Su(A)x is a modified sugar moiety comprising one or more functional groups A. Functional group A is independently selected from the group consisting of a thiol group, a halogen, a sulfonyloxy group, a halogenated acetamido group, a mercaptoacetamido group and a sulfonated hydroxyacetamido group. The invention also relates to a glycoprotein-conjugate wherein a glycoprotein according to the invention is conjugated to a molecule of interest. Said molecule of interest may for example be an active substance. The invention further relates to a process for the preparation of a modified glycoprotein, and to a method for the preparation of a glycoprotein-conjugate. The invention particularly relates to modified antibodies, antibody-conjugates, antibody-drug conjugates and methods for the preparation thereof.