The ectodomain contains 13 potential N-linked glycosylation sites(NXT/NXS),2 calcium binding domains[DX(D/N)XDGXXD],18 cysteine residues,and a proteolytic cleavage site located between amino acid residue 890 and 891(KR-D).

• 在890和891位氨基酸之间有1个蛋白酶裂解位点(KR-D); 胞外域含有13个潜在的糖基化位点(NXT/NXS)、2个Ca2+结合位点[DX(D/N)XDGXXD]、18个半胱氨酸残基。