Structural differences found in the sugar chains of eutopic and ectopic free α-subunits of human glycoprotein hormone

Abstract Free α-subunits of human glycoprotein hormone were purified from the urine of a healthy pregnant woman and from that of a patient with adenocarcinoma. Comparative study of their sugar moieties revealed that they have different numbers and different sets of asparagine-linked sugar chains, which are also different from those of α-subunit obtained by dissociation of whole hCG molecule. The eutopic free α-subunit contained biantennary complex-type sugar chains only. In contrast, the ectopic free α-subunit contained tri- and tetraantennary complex-type sugar chains in addition.