Title : Localization of an O-glycosylation
site in the
alpha-subunit of the human platelet integrin
GPIIb /IIIa involved in Baka (
HPA-3a) alloantigen expression
Abstract :
- The human alloantigen system Baka/b is associated with a Ile843--> Ser replacement on platelet glycoprotein IIb , the alpha- subunit of the integrin receptor for fibrinogen ( GPIIb /IIIa)
- Recent immunological studies indicate that sialylated oligosaccharide chain(s) are also implicated in expression of the Baka determinant
- Here we show that the GPIIb fragment 704-856 contains the whole Baka epitope , and that chemical cleavage of a single O-linked oligosaccharide chain within this GPIIb domain correlates with the loss of its anti-Baka antibodies binding ability
- Ser847 was identified as the O-glycosylation site
- Therefore, our results show that the Ser847 modification is responsible for the expression of the GPIIb-specific Baka alloantigen, and provide thus a link between the molecular biology and the immunologic observations